\nThe Web Development Glossary

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\nIntroduction\n
\nAcknowledgments\n
\nThe Web Development Glossary\n
\n!./_\n
\n0–9\n
\nA\n
\nB\n
\nC\n
\nD\n
\nE\n
\nF\n
\nG\n
\nH\n
\nI\n
\nJ\n
\nK\n
\nL\n
\nM\n
\nN\n
\nO\n
\nP\n
\nQ\n
\nR\n
\nS\n
\nT\n
\nU\n
\nV\n
\nW\n
\nX\n
\nY\n
\nZ\n
\nAppendix\n
- \nWikipedia Contributions\n
- \nMDN Web Docs Contributions\n
\n
\nFeedback\n
\nAbout The Web Development Glossary\n

\nIntroduction

\n\n

This is a glossary for web development.

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It covers more than 2,000 [with the latest update more than 3,000] important, useful, and historic terms and abbreviations relevant for web (and software) developers.

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The glossary acquaints and reunites you with the major standards and concepts of the Web, with HTML, CSS, JavaScript, accessibility, security, performance, code quality, internationalization, localization, editors and tooling and more. It then goes beyond web development, touching on computer science, design, typography, usability and user experience, information as well as project management, other disciplines of interest and relevance to the modern developer. It goes beyond, inspiring the curiosity to learn more about the Web and the people creating and using it.

\n\n

The glossary does not tell a story in the same way as other books do, but it still tells a story. It tells a story that is sterile yet messy. It tells a story that only started three decades ago and that is still unfolding. It tells a story that starts with you. Why you? Because you are at your own stage of web development—and because web development is only unfolding, only so alive, because of people like you, people who take a personal interest in it. When you read the glossary like you would read another book, you may notice. (Yet still, it is a glossary.)

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⁂

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Many explanations and definitions in this glossary are based on Wikipedia and the MDN Web Docs. It was neither necessary nor desirable to come up with a new and different explanation for every term.

\n\n

Arrows (“→”) point to the expanded forms of abbreviations, and to the more common synonyms and expressions. Sometimes they take you on a little detour, but only to be transparent about the journey taken (like Personal Home Page → PHP → Hypertext Preprocessor, or HTML 5 → HTML → Hypertext Markup Language). This may seem lengthy, but it aims to make meanings, relationships, and sometimes history more clear. An arrow may also point at a term that encompasses the referring term, or at a related concept, and therefore does not necessarily indicate identity or equivalence.

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Whenever there is a source of great quality or immediate use, explanations include references to external documentation and software.

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Some terms and abbreviations have several meanings. Only the tech-related ones are shown.

\n\n

Sometimes there is imprecision: Is a home page a special type of web page, but a homepage another word for a website? (Per this book, trying to gauge how “most” people use the respective terms, this is so.)

\n\n

Unfortunately, there are going to be inconsistencies, probably errors, and perhaps also controversy. Please help improve the glossary as well as, if applicable, Wikipedia and MDN Web Docs. Giving back to the communities, work on the book has led to numerous small improvements to both Wikipedia and MDN Web Docs articles, but it is unlikely that these improvements covered all there was to improve. Thank you for sharing your knowledge and taking the time to contribute as well.

\n\n

This all being said: Enjoy. Web development is a great field.

\n\n\n\n\n

\nAcknowledgments

\n\n

The Web Development Glossary would not have been possible without help. I thank Gabriele Kretzschmar for review of the manuscript, and Ganesh Subramanian and Yaroslav Kiyenko for advice on book details. I am also grateful to Wikipedia, the MDN Web Docs, and all their contributors for their own work mapping the web development landscape, and allowing others to build on that work. Thank you.

\n\n

I also thank Lucas Frank Weatherhog, Dan Shappir, Shaun O’Connell, Moritz Glantz, J. Albert Bowden II, Tommy Williams, and Kirsty MacRae who contributed with corrections and suggestions to the glossary, as well as Red Onion for their friendly support.

\n\n\n\n\n

\nThe Web Development Glossary

\n\n\n

\n!./_

\n\n

!important: An indicator for a declaration that, by virtue of the CSS cascade, is to take precedence over a normal declaration.
.gitignore: A plain-text file that, one per line, contains patterns for files and directories to be ignored by Git version control.
.htaccess: A directory-level configuration file supported by several web servers, used for the configuration of website access issues, such as URL redirection, URL shortening, access control, and more. A site could have more than one .htaccess file, and the files are placed inside the web tree (i.e., inside directories and their subdirectories). .htaccess files act as a subset of the server’s global configuration file (like httpd.conf) for the directory that they are in, or all subdirectories. The original purpose of .htaccess—reflected in its name—was to allow per-directory access control by, for example, requiring a password to access web content. More commonly, however, the .htaccess files define or override many other configuration settings such as content type, character set, CGI handlers, etc. †\n
.htpasswd: A flat file used to store usernames and password for basic authentication on an Apache HTTP Server. The name of the file is given in the .htaccess configuration, and can be anything although “.htpasswd” is the canonical name. .htpasswd is often maintained with the shell command “htpasswd” which can add, delete, and update users, and will properly encode the password for use (so that it is easily checked, but not reversed back to the original password). The file consists of rows, each row corresponding to a username, followed by a colon, followed by a string containing the hashed password optionally prepended by an algorithm specifier ( $2y$ , $apr1$ , or {SHA}) or salt. The hash historically used “Unix crypt” style with MD5 or SHA1 as common alternatives, although as of version 2.2.18 a variant of MD5 is now the default. †\n
.NET: → .NET Framework
.NET Framework: A software framework developed by Microsoft that runs primarily on Microsoft Windows. The .NET Framework includes a large class library named as Framework Class Library (FCL) and provides language interoperability (each language can use code written in other languages) across several programming languages. Programs written for the .NET Framework execute in a software environment (in contrast to a hardware environment) named the Common Language Runtime (CLR). The CLR is an application virtual machine that provides services such as security, memory management, and exception handling. As such, computer code written using the .NET Framework is called managed code. FCL and CLR together constitute the .NET Framework. .NET was first released in 2002. † ℹ︎ dotnet.microsoft.com\n
/dev/null: → Null device
__qem: A proprietary, unofficial CSS unit (“quirky em”) to manage margins in reflow roots (body, th, and td) similar to the Internet Explorer web browser. According to the source code, “When the quirky value is used, if you’re in quirks mode, the margin will collapse away inside a table cell.” __qem was originally spelled with one underscore, _qem.

\n\n\n\n\n

\n0–9

\n\n

8.3: A filename convention used by old versions of DOS and versions of Microsoft Windows prior to Windows 95 and Windows NT 3.5. 8.3 is also used in modern Microsoft operating systems as an alternate filename to the long filename for compatibility with legacy programs. 8.3 filenames are limited to at most eight characters (after any directory specifier), followed optionally by a filename extension consisting of a period (“.”) and at most three further characters. †\n
11ty: → Eleventy
20: FTP data transfer TCP port number.
21: FTP control TCP port number.
22: SSH TCP port number.
23: Telnet TCP port number.
25: Simple Mail Transfer Protocol (SMTP) TCP port number.
2FA: → Two-factor authentication
53: Domain Name System (DNS) TCP and UDP port number.
70: Gopher TCP port number.
79: Finger TCP and UDP port number.
80: Hypertext Transfer Protocol (HTTP) TCP port number.
88: Kerberos authentication TCP and UDP port number.
100: “Continue” HTTP status code.
101: “Switching Protocols” HTTP status code.
102: “Processing” HTTP status code (WebDAV).
109: Post Office Protocol (POP2) TCP port number.
110: Post Office Protocol (POP3) TCP port number.
143: Internet Message Access Protocol (IMAP) TCP port number.
200: “OK” HTTP status code.
201: “Created” HTTP status code.
202: “Accepted” HTTP status code.
203: “Non-Authoritative Information” HTTP status code.
204: “No Content” HTTP status code.
205: “Reset Content” HTTP status code.
206: “Partial Content” HTTP status code.
207: “Multi-Status” HTTP status code (WebDAV).
220: Internet Message Access Protocol (IMAP) TCP and UDP port number.
226: “IM Used” HTTP status code.
300: “Multiple Choices” HTTP status code.
301: “Moved Permanently” HTTP status code.
302: “Found” (previously “Moved Temporarily”) HTTP status code.
303: “See Other” HTTP status code.
304: “Not Modified” HTTP status code.
305: “Use Proxy” HTTP status code.
306: Now unused, former “Switch Proxy” HTTP status code.
307: “Temporary Redirect” HTTP status code.
308: “Permanent Redirect” HTTP status code.
389: Lightweight Directory Access Protocol (LDAP) TCP port number.
400: “Bad Request” HTTP status code.
401: “Unauthorized” HTTP status code.
403: “Forbidden” HTTP status code.
404: “Not Found” HTTP status code.
405: “Method Not Allowed” HTTP status code.
406: “Not Acceptable” HTTP status code.
407: “Proxy Authentication Required” HTTP status code.
408: “Request Timeout” HTTP status code.
409: “Conflict” HTTP status code.
410: “Gone” HTTP status code.
411: “Length Required” HTTP status code.
412: “Precondition Failed” HTTP status code.
413: “Request Entity Too Large” HTTP status code.
414: “Request-URI Too Long” HTTP status code.
415: “Unsupported Media Type” HTTP status code.
416: “Requested Range Not Satisfiable” HTTP status code.
417: “Expectation Failed” HTTP status code.
418: “I’m a teapot” HTTP status code, a 1998 IETF April Fools’ joke.
421: “Misdirected Request” HTTP status code.
422: “Unprocessable Entity” HTTP status code (WebDAV).
423: “Locked” HTTP status code (WebDAV).
424: “Failed Dependency” HTTP status code (WebDAV).
425: “Too Early” HTTP status code.
426: “Upgrade Required” HTTP status code.
428: “Precondition Required” HTTP status code.
429: “Too Many Requests” HTTP status code.
431: “Request Header Fields Too Large” HTTP status code.
443: Hypertext Transfer Protocol Secure (HTTPS) TCP port number.
451: “Unavailable For Legal Reasons” HTTP status code.
500: “Internal Server Error” HTTP status code.
501: “Not Implemented” HTTP status code.
502: “Bad Gateway” HTTP status code.
503: “Service Unavailable” HTTP status code.
504: “Gateway Timeout” HTTP status code.
505: “HTTP Version Not Supported” HTTP status code.
507: “Insufficient Storage” HTTP status code (WebDAV).
511: “Network Authentication Required” HTTP status code.
992: Telnet over TLS/SSL TCP and UDP port number.
993: Internet Message Access Protocol over TLS/SSL (IMAPS) TCP port number.
995: Post Office Protocol 3 over TLS/SSL (POP3S) TCP and UDP port number.

\n\n\n\n\n

\nA

\n\n

A: An IPv4 address resource record in the Domain Name System (DNS). †\n
A List Apart: A popular online magazine that “explores the design, development, and meaning of web content, with a special focus on web standards and best practices.” A List Apart was founded in 1998. ℹ︎ alistapart.com\n
A/B testing: A user experience research methodology. A/B tests consist of a randomized experiment with two variants, A and B. A/B testing includes the application of statistical hypothesis testing or “two-sample hypothesis testing” as used in the field of statistics. It is a way to compare two versions of a single variable, typically by testing a subject’s response to variant A against variant B, and determining which of the two variants is more effective. †\n
A11Y: → Accessibility
AAA: → Arrange, Act, Assert
AAAA: An IPv6 address resource record in the Domain Name System (DNS). †\n
Above the fold: The part of a web page that is visible without scrolling.
Absolute domain name: → Fully qualified domain name
Abstract Data Type: A mathematical model for data types, where a data type is defined by its behavior (semantics) from the point of view of a user of the data, specifically in terms of possible values, possible operations on data of this type, and the behavior of these operations. †\n
Abstraction: A way to reduce complexity and allow efficient design and implementation in complex software systems. Abstractions hide the technical complexity of systems behind simpler APIs. ‡\n
Accelerated Mobile Pages: A web component framework and a website publishing technology developed by Google which has the mission to “provide a user-first format for web content.” The AMP framework consists of three components: AMP HTML, which is standard HTML markup with web components, AMP JavaScript, which manages resource loading, and AMP caches, which serve and validate AMP pages. Most AMP pages are delivered by Google’s AMP cache. AMP was released in 2015. † ℹ︎ amp.dev\n
Accept-CH: An HTTP header that is used to specify which Client Hints headers a client should include in subsequent requests. ‡\n
Acceptance Test-Driven Development: A development methodology based on communication between the business customers, the developers, and the testers. ATDD aids developers and testers in understanding the customer’s needs prior to implementation, and allow customers to be able to converse in their own domain language. †\n
Acceptance testing: A test conducted to determine if the requirements of a specification or contract are met. In systems engineering it may involve black-box testing performed on a system prior to its delivery. In software testing the ISTQB (International Software Testing Qualifications Board) defines acceptance testing as formal testing with respect to user needs, requirements, and business processes conducted to determine whether a system satisfies the acceptance criteria and to enable users, customers, or other authorized entities to determine whether to accept the system. Acceptance testing is also known as user acceptance testing (UAT), end user testing, operational acceptance testing (OAT), acceptance test-driven development (ATDD), or field (acceptance) testing. Acceptance criteria are the criteria that a system or component must satisfy in order to be accepted by a user, customer, or other authorized entity. †\n
Access control: The selective restriction of access to a place or other resource, while access management describes the process. The act of accessing may mean consuming, entering, or using. †\n
Access Control List: A list of permissions associated with an object. An ACL specifies which users or system processes are granted access to objects, as well as what operations are allowed on given objects. Each entry in a typical ACL specifies a subject and an operation. †\n
Access key: In accessibility, a shortcut to jump to a specific web page via the keyboard. Access keys were introduced in 1999 and quickly achieved near-universal browser support. †\n; In computer security, security credentials that consist of an access key ID and a secret access key.
Access logs: → Server logs
Access token: A token that contains the security credentials for a login session and that identifies a user, a user’s groups, a user’s privileges, and, in some cases, a particular application. Typically, one may be asked to enter an access token (e.g., 40 random characters) rather than the usual password (an access token should therefore be kept secret just like a password). †\n
Accessibility: The design and development of products, devices, services, and environments so that they are usable by people with disabilities. In the context of the Web it means to make information and services usable by as many people as possible. †\n
Accessibility Conformance Testing: A rule format for the testing of conformance with accessibility standards. ℹ︎ w3.org/WAI/standards-guidelines/act\n
Accessibility Object Model: A representation of the DOM that is being used by assistive technology. ℹ︎ wicg.github.io/aom/spec\n
Accessibility tree: → Accessibility Object Model
Accessible Rich Internet Applications: A collection of roles, states, and properties that define accessible user interface elements and can be used to improve the accessibility and interoperability of web content and applications. ℹ︎ w3.org/TR/wai-aria\n
ACID: → Atomicity, Consistency, Isolation, Durability
Acid tests: A range of web standards compliance tests that were set up in 1999 (Acid1), 2005 (Acid2), and 2008 (Acid3). ℹ︎ acidtests.org\n
ACK: A signal that is passed between communicating processes, computers, or devices to signify acknowledgement, or receipt of message, as part of a communications protocol like the Transmission Control Protocol (TCP). †\n
ACL: → Access Control List
ACM: → Association for Computing Machinery
Acq-hiring: → Acqui-hiring
Acqui-hiring: The process of acquiring a company primarily to recruit its employees, rather than its products or services. “Acqui-hiring” is a portmanteau of “acquisition” and “hiring.” The term was first used in 2005. †\n
ACSS: → Atomic CSS
ACT: → Accessibility Conformance Testing
Action item: → Todo
ActionScript: An object-oriented programming language originally developed by Macromedia (later acquired by Adobe). ActionScript is influenced by HyperTalk, the scripting language for HyperCard. It is now an implementation of ECMAScript, though it originally arose as a sibling, both being influenced by HyperTalk. ActionScript is used primarily for the development of websites and software targeting the Adobe Flash Player platform, used on web pages in the form of embedded SWF files. †\n
Active redundancy: A design concept that increases operational availability and that reduces operating cost by automating critical maintenance actions. †\n
Active Server Pages: A server-side script engine for dynamically generated web pages. ASP can be written in a scripting language such as VBScript, JScript, or PerlScript. ASP were introduced in 1996 by Microsoft. †\n
Active Users: A performance metric for the success of an Internet product such as a social networking service, online game, or mobile app. It measures how many users visit or interact with the product or service over a given interval. This metric is commonly assessed per month as monthly active users (MAU), per week as weekly active users (WAU), or per day as daily active users (DAU). †\n
ActiveX: A software framework that allows applications to share information and functionality, based on the Component Object Model (COM) and Object Linking and Embedding (OLE). ActiveX was introduced in 1996 by Microsoft.
Adaptive: An aspect of or synonym for agile development.
Adaptive loading: The loading of web resources depending on the connection type and speed.
Adaptive technology: Technology specifically designed for and used by people with disabilities. Adaptive technology often refers to electronic and information technology access. It is a subset of assistive technology. †\n
Addon: → Plugin
Address Resolution Protocol: A communication protocol used for discovering the link layer address, such as a MAC address, associated with a given internet layer address, typically an IPv4 address. This mapping is a critical function in the Internet protocol suite. ARP was defined in 1982 by RFC 826, which is Internet Standard STD 37. †\n
Adobe ColdFusion: → ColdFusion
Adobe Dreamweaver: → Dreamweaver
Adobe Flash: → Flash
Adobe Photoshop: → Photoshop
ads.txt: An initiative from the IAB Technology Laboratory that specifies an “ads.txt” text file that companies can host on their web servers, listing the other companies authorized to sell their products or services. This is designed to allow online buyers to check the validity of the sellers from whom they buy, for the purposes of Internet fraud prevention. ads.txt was introduced in 2017. †\n
ADT: → Abstract Data Type
Advanced Encryption Standard: A specification for the encryption of electronic data established in 2001 by the US National Institute of Standards and Technology (NIST). AES is a subset of the Rijndael block cipher developed by Vincent Rijmen and Joan Daemen. For AES, NIST selected three members of the Rijndael family, each with a block size of 128 bits, but three different key lengths: 128, 192, and 256 bits. †\n
Advanced Package Tool: A software user interface that works with core libraries to handle the installation and removal of software on Debian, Ubuntu, and related Linux distributions. APT simplifies the process of managing software on Unix-like computer systems by automating the retrieval, configuration, and installation of software packages. †\n
Advanced Persistent Threat: A stealthy threat actor, typically a nation state or state-sponsored group, which gains unauthorized access to a computer network and remains undetected for an extended period. In recent times, the term may also refer to non-state-sponsored groups conducting large-scale targeted intrusions for specific goals. The median time an APT attack goes undetected differs widely between regions. †\n
AES: → Advanced Encryption Standard
Affordance: Those action possibilities that are readily perceivable by an actor, that is, an affordance suggests how an object may be interacted with. For example, an underlined word on a web page has the affordance of being clickable. †\n
Agile: An umbrella term for approaches to project management and software development under which self-organizing, cross-functional teams cooperate with customers and users to produce requirements and solutions. Agile advocates adaptive planning, evolutionary development, early delivery, continuous improvement, and encourages rapid and flexible response to change. †\n
Agile Manifesto: → Manifesto for Agile Software Development
AirMosaic: An early commercial web browser based on the NCSA Mosaic browser. AirMosaic was released in 1994. †\n
AJAX/Ajax: → Asynchronous JavaScript and XML
ALA: → A List Apart
ALGOL: → Algorithmic Language
Algorithm: A finite sequence of well-defined, computer-implementable instructions, typically to solve a class of problems or to perform a computation. Algorithms are unambiguous specifications for performing calculation, data processing, automated reasoning, and other tasks. †\n
Algorithmic Language: A family of imperative computer programming languages, originally developed in the mid-1950s, which greatly influenced many other languages and was the standard method for algorithm description used by the Association for Computing Machinery (ACM) in textbooks and academic sources for more than 30 years. †\n
Aliasing: An effect that causes different signals to become indistinguishable (or aliases of one another) when sampled. Aliasing also often refers to the distortion or artifact that results when a signal reconstructed from samples is different from the original continuous signal. Aliasing can occur in signals sampled in time, for instance digital audio, and is referred to as temporal aliasing. It can also occur in spatially sampled signals (e.g., moiré patterns in digital images); this type of aliasing is called spatial aliasing. Aliasing is generally avoided by applying low pass filters or anti-aliasing filters (AAF) to the input signal. †\n
Almost standards mode: → Almost strict mode
Almost strict mode: A third web browser compatibility mode (beside strict and quirks mode) which maintains the “traditional” vertical sizing of table cells according to the CSS 2 specification, and which treats images like block elements. †\n
ALPN: → Application-Layer Protocol Negotiation
Alternate style sheet: A style sheet mutually exclusive to other style sheets, which can be selected for alternative styling. An alternate style sheet is indicated through the alternate keyword, as in <link rel=\"alternate stylesheet\" href=example.css title=Example>.
Amaya: A web editor with browsing capabilities. Amaya was developed by the World Wide Web Consortium (W3C) and INRIA from 1996 to 2012.
Amazon Resource Name: A unique identifier for an Amazon Web Services (AWS) resource. An ARN follows the format arn:partition:service:region:account-id:resource-id, arn:partition:service:region:account-id:resource-type/resource-id, or arn:partition:service:region:account-id:resource-type:resource-id.
Amazon Route 53: → Route 53
Amazon S3: → S3
Amazon Silk: → Silk
Amazon Simple Queue Service: → SQS
Amazon Simple Storage Service: → Amazon S3
Amazon SQS: → SQS
Amazon Virtual Private Cloud: → Amazon VPC
Amazon VPC: A commercial cloud computing service that provides users a virtual private cloud, by provisioning a logically isolated section of the Amazon Web Services (AWS) cloud. † ℹ︎ aws.amazon.com/vpc\n
Amazon Web Services: A subsidiary of Amazon that provides on-demand cloud computing platforms and APIs on a metered pay-as-you-go basis. In aggregate, these cloud computing web services provide a set of primitive abstract technical infrastructure and distributed computing building blocks and tools. AWS technology is implemented at server farms throughout the world. † ℹ︎ aws.amazon.com\n
AMD: → Asynchronous Module Definition
American National Standards Institute: A private non-profit organization that, per its mission, “enhances both the global competitiveness of US business and the US quality of life by promoting and facilitating voluntary consensus standards and conformity assessment systems, and safeguarding their integrity.” The ANSI was founded in 1918. ℹ︎ ansi.org\n
American Standard Code for Information Interchange: A character encoding standard for electronic communication. ASCII was conceived in 1960 and published in 1963 by the ASA (American Standards Association), now ANSI.
AMP: → Accelerated Mobile Pages
Analytics: → Web analytics
Anchor: Technical name for a link, usually referring to the a element.
Angular: A TypeScript-based web application framework developed by Google and a community of individuals and corporations. Angular is a complete rewrite from the same team that built AngularJS. Angular was released in 2016. † ℹ︎ angular.io\n
AngularJS: A JavaScript-based frontend web framework mainly maintained by Google and a community of individuals and corporations to address challenges encountered in developing single-page applications (SPAs). AngularJS aims to simplify both the development and the testing of such applications by providing a framework for client-side model-view-controller (MVC) and model-view-viewmodel (MVVM) architectures, along with components commonly used in rich Internet applications. AngularJS was first released in 2010 and makes for the frontend part of the MEAN stack. Google no longer updates AngularJS, and the Angular team recommends upgrading to Angular as the best path forward. † ℹ︎ angularjs.org\n
Animation: A method in which images and graphics are manipulated to appear as moving. In web development, animations are often created using CSS (CSS Animations, CSS Transitions) or JavaScript. †\n
Anonymous block box: Within a block container box, a block-level box forced by the presence of other block-level boxes. In <div>Some text<p>More text</div>, “Some text” resides in an anonymous block-level box because <p> spawns a block-level box.
Anonymous block element: → Anonymous block box
Anonymous function: A function definition that is not bound to an identifier. Anonymous functions are often arguments being passed to higher-order functions, or used for constructing the result of a higher-order function that needs to return a function. If the function is only used once, or a limited number of times, an anonymous function may be syntactically lighter than using a named function. Anonymous functions are ubiquitous in functional programming languages and other languages with first-class functions. †\n
Anonymous inline box: An inline box that does not have an associated inline-level element.
Anonymous inline element: Any text that is directly contained inside a block container element that is not inside an inline element.
Anonymous text: Any string of characters that is not contained within an inline element.
ANSI: → American National Standards Institute
Anti-pattern: A common response to a recurring problem that is usually ineffective and risks being highly counterproductive, and that has more negative than positive consequences. †\n
AOM: → Accessibility Object Model
AOMedia Video 1: A video coding format initially designed for video transmissions over the Internet. AV1 was developed as a successor to VP9 by the Alliance for Open Media (AOMedia), a consortium founded in 2015. † ℹ︎ aomedia.org/av1-features\n
Apache: → Apache HTTP Server
Apache HTTP Server: A cross-platform web server. The Apache server was first released in 1995. ℹ︎ httpd.apache.org\n
Apache Maven: → Maven
Apache Subversion: → Subversion
Apache Tomcat: → Tomcat
Apache Weex: → Weex
API: → Application Programming Interface
API gateway: An entry point for a system of application programming interfaces (APIs) that takes care of request routing as well as protocol translation. An API gateway also helps mitigate backend issues, for example by offering fallback or cached data.
App: → Application
App shell: The minimal HTML, CSS, and JavaScript necessary to provide a site or app user interface.
Apple Safari: → Safari
Apple Universal Access: → Universal Access
Applet: Any small application that performs a specific task that runs within the scope of a dedicated widget engine or a larger program, often as a plugin. Usually referring to a Java applet, a program written in the Java programming language that is designed to be placed on a web page. An applet is not a full-featured application program but intended to be easily accessible. †\n
Application: A computer program designed to help people perform an activity. An application differs from an operating system (which runs a computer), a utility (which performs maintenance or general-purpose chores), and a programming tool (with which computer programs are created). Depending on the activity for which it was designed, an application can manipulate text, numbers, audio, graphics, and a combination of these elements. Some application packages focus on a single task, such as word processing; others, called integrated software, include several applications. †\n
Application context: A top-level browsing context that has a manifest applied to it. ‡\n
Application Programming Interface: An interface or communication protocol between different parts of a computer program intended to simplify the implementation and maintenance of software. An API may be for a web-based system, operating system, database system, computer hardware, or software library. †\n
Application-Layer Protocol Negotiation: A TLS extension which indicates what application layer protocol is negotiating the encrypted connection without requiring additional round trips. ALPN was specified in 2014 as RFC 7301. ‡\n
APT: → Advanced Package Tool; → Advanced Persistent Threat
AR: → Augmented Reality
Arena: One of the first web browsers for Unix. Originally developed in 1993 by Dave Raggett, development continued at CERN and the World Wide Web Consortium (W3C) and subsequently by Yggdrasil Computing. Arena was used in testing the implementations for HTML 3.0, Cascading Style Sheets (CSS), Portable Network Graphics (PNG), and libwww. Arena was widely used and popular at the beginning of the World Wide Web. †\n
Argument: The actual input expression passed or supplied to a function, procedure, or routine in a call or invocation statement. †\n
ARIA: → Accessible Rich Internet Applications
ARIA roles: A set of predefined names that can be used to specify the meaning and purpose of markup elements. Roles can cover abstract use cases, widgets, document structure, landmarks, live regions, and windows, and are set using the role attribute.
ARN: → Amazon Resource Name
ARP: → Address Resolution Protocol
Arrange, Act, Assert: A pattern to organize test methods by.
Array: A data structure consisting of a collection of elements (values or variables), each identified by at least one array index or key. An array is stored such that the position of each element can be computed from its index tuple. The simplest type of data structure is a linear array, also called one-dimensional array. †\n
Arrow function: An anonymous function and syntactically compact alternative to a regular function expression, although without its own bindings to the this, arguments, super, or new.target keywords. ‡\n
ASCII: → American Standard Code for Information Interchange
ASI: → Automatic Semicolon Insertion
ASP: → Active Server Pages
ASP.NET: A server-side web application framework designed to build dynamic websites, applications, and services. ASP.NET was first released in 2002 with version 1.0 of the .NET Framework, and is the successor to Microsoft’s Active Server Pages (ASP) technology. † ℹ︎ dotnet.microsoft.com/apps/aspnet\n
Aspect ratio: A proportional relationship between an image’s width and height. The aspect ratio is commonly expressed as two numbers separated by a colon, as in 16:9. †\n
AssemblyScript: A TypeScript-based programming language (essentially JavaScript with static types) that is optimized for WebAssembly and compiled to WebAssembly using asc, the reference AssemblyScript compiler. AssemblyScript is developed by the AssemblyScript Project and the AssemblyScript community. It was first released in 2017. † ℹ︎ assemblyscript.org\n
Assignment: The setting or resetting of the value stored in the storage location(s) denoted by a variable name; in other words, an assignment statement copies a value into the variable. In most imperative programming languages, the assignment statement (or expression) is a fundamental construct. Today, the most commonly used notation for this basic operation has come to be x = expr (originally Superplan 1949–51, popularized by Fortran 1957 and C) followed by x := expr (originally ALGOL 1958, popularized by Pascal), although there are many other notations in use. †\n
Assistive technology: Assistive, adaptive, and rehabilitative devices and software for people with disabilities or the elderly population. Assistive technology can ameliorate the effects of disabilities that limit the ability to perform activities of daily living. †\n
Assistive Technology Service Provider Interface: A platform-neutral framework for providing bidirectional communication between assistive technologies (AT) and applications. AT-SPI is the de facto standard for providing accessibility to free and open desktops, like GNU/Linux or OpenBSD. It is led by the GNOME Project. †\n
Association for Computing Machinery: An international learned society for computing. The ACM was founded in 1947, and is the world’s largest scientific and educational computing community. Its motto is “Advancing Computing as a Science and Profession.” † ℹ︎ acm.org\n
Asynchronous: The occurrence of events independent of the main program flow. A common way for dealing with asynchrony in is to provide subroutines that return to their caller an object, sometimes called a future or promise, that represents the ongoing events. †\n
Asynchronous Module Definition: A specification for the JavaScript programming language. AMD defines an API that defines code modules and their dependencies, and loads them asynchronously if desired. Implementations of AMD promise website performance improvements, because AMD implementations load smaller JavaScript files, and then only when they are needed. AMD implementations also suggest fewer page errors, because developers can define dependencies that must load before a module is executed, so the module does not try to use outside code that is not available yet. † ℹ︎ github.com/amdjs/amdjs-api\n
Asynchronous JavaScript and XML: A set of web development techniques using web technologies on the client side to create asynchronous web applications. With AJAX, web applications can send and retrieve data from a server asynchronously (in the background) without interfering with the display and behavior of the existing page. By decoupling the data interchange layer from the presentation layer, AJAX allows web pages and applications to change content dynamically without the need to reload the entire page. In practice, modern implementations commonly utilize JSON instead of XML. †\n
at: A command on Unix-like operating systems, Microsoft Windows, and ReactOS used to schedule commands to be executed once, at a particular time in the future. †\n
AT: → Assistive technology
at-rule: A CSS statement starting with an at-keyword (@ and an identifier, as with @import). The at-rule holds until either the next semicolon or the next block.
AT-SPI: → Assistive Technology Service Provider Interface
ATAG: → Authoring Tool Accessibility Guidelines
ATDD: → Acceptance Test-Driven Development
Atlassian Bitbucket: → Bitbucket
Atlassian Jira: → Jira
Atom: An XML-based feed format consisting of two web standards, the Atom Syndication Format and the Atom Publishing Protocol (AtomPub or APP).
Atomic CSS: A CSS architecture that is based on “single-purpose units of style” applied via “short, predictable class names.” ℹ︎ acss.io\n
Atomicity, Consistency, Isolation, Durability: A set of properties of database transactions intended to guarantee validity even in the event of errors, power failures, etc. In the context of databases, a sequence of database operations that satisfies the ACID properties (which can be perceived as a single logical operation on the data) is called a transaction. The acronym was coined in 1983 by Andreas Reuter and Theo Härder. †\n
Attribute: A property of an object, element, or file. An attribute may also refer to or set the specific value for a given instance. An attribute of an object usually consists of a name and a value; of an element, a type or class name; of a file, a name and extension. Attributes should be considered metadata. †\n
Attribute minimization: The valid option for a Boolean attribute not to have a value if it is set (and therefore true). In XML-based languages, attribute minimization is disallowed and attributes must have a value; for example, checked is suggested to be written checked=\"checked\".
Augmented Reality: An interactive experience of a real-world environment where the objects that reside in the real world are enhanced by computer-generated perceptual information, sometimes across multiple sensory modalities, including visual, auditory, haptic, somatosensory, and olfactory. AR can be defined as a system that fulfills three basic features: a combination of real and virtual worlds, real-time interaction, and accurate 3D registration of virtual and real objects. †\n
Authentication: The act of proving an assertion, such as the identity of a computer system user. In contrast with identification, the act of indicating a person or thing’s identity, authentication is the process of verifying that identity. †\n
Authoring tool: Software that enables the creation of digital content.
Authoring Tool Accessibility Guidelines: Guidelines for designing web content authoring tools that are accessible to authors with disabilities and designed to enable, support, and promote the production of more accessible web content by all authors. ATAG 1.0 became a W3C Recommendation in 2000, and ATAG 2.0 in 2015. ℹ︎ w3.org/TR/ATAG20\n
Authorization: The specifying of access rights and privileges to resources, which is related to information security and computer security in general, and to access control in particular. More formally, “to authorize” is to define an access policy. †\n
Automagic: A blend of “automatic” and “magic,” referring to an action that is performed automatically but also in a way as to seem magical.
Automatic Semicolon Insertion: An ECMAScript feature in which a semicolon is automatically inserted when two statements are separated by a line ending or a closing brace (}), or if a line ending follows either of break, continue, return, or throw (restricted production).
Automation: A technology by which a process or procedure is performed with minimal human assistance. Automation or automatic control is the use of various control systems for operating equipment. †\n
Autonomous custom element: One type of custom element for a web component. An autonomous custom element is standalone, that is, it does not inherit from standard HTML elements. Autonomous custom elements are used by literally writing them out as HTML elements. ‡\n
AV1: → AOMedia Video 1
AV1 Image File Format: An image file format that uses AV1 compression algorithms. AVIF competes with HEIC which uses the same container format, built upon ISOBMFF, but HEVC for compression. Version 1.0.0 of the AVIF specification was finalized in 2019. †\n
Availability Zone: With Amazon Web Services (AWS), a term for one or more data centers with redundant power, networking, and connectivity. An AWS Region consists of several Availability Zones.
AVIF: → AV1 Image File Format
AWS: → Amazon Web Services
AZ: → Availability Zone

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BA: → Basic access authentication
Babel: A JavaScript transpiler that is mainly used to convert ECMAScript 2015+ (ES6+) code into a backwards-compatible version of JavaScript that can be run by older JavaScript engines. † ℹ︎ babeljs.io\n
Back/forward cache: A browser optimization to improve the web browsing experience. Bfcache is an in-memory cache that stores a complete snapshot of a web page to enable fast back and forward navigation.
Backend: The data access layer of software of a piece of software, usually covering business logic and data storage. In the client-server model, the server is considered the back end. †\n
Backend for Frontend: The concept of having separate backends per application or interface, to act as intermediaries between the respective frontends and the underlying services. BFF was introduced in 2015 by Sam Newman.
Backlink: A link from one web resource (the referrer) to another web resource (the referent), made by an anchor, as viewed from the web resource being referred to. Other words for “backlink” are “incoming link,” “inbound link,” “inlink,” “inward link,” and “citation.” †\n
Backup: A copy of computer data taken and stored elsewhere so that it may be used to restore the original after a data loss event. The verb form, referring to the process of doing so, is “to back up,” whereas the noun and adjective form is “backup.” Backups can be used to recover data after its loss from data deletion or corruption, or to recover data from an earlier time. Backups provide a simple form of disaster recovery. †\n
Backup redundancy: → Standby redundancy
Backward compatibility: A property of a product, system, or technology that allows for interoperability with an older legacy system, or with input designed for such a system, especially in telecommunications and computing. Modifying a system in a way that does not allow backward compatibility is sometimes called breaking backward compatibility. †\n
Bad Neighborhood: Bad quality websites, or websites that are being penalized and downgraded by search engines. Search engine optimization (SEO) best practices suggest to avoid links to and from bad neighborhood websites.
Bada: A discontinued operating system for mobile devices such as smartphones and tablet computers. Bada was developed by Samsung. Its name is derived from “바다” (“bada”), meaning “ocean” or “sea” in Korean. Bada was released in 2010 and discontinued in 2013. †\n
Bandwidth: The maximum rate of data transfer across a given path. Bandwidth may be characterized as network bandwidth, data bandwidth, or digital bandwidth. †\n
Banner: An online advertising format, usually a horizontal or vertical rectangle in standardized sizes.
Barrierefreie-Informationstechnik-Verordnung: German accessibility regulations. ℹ︎ www.gesetze-im-internet.de/bitv_2_0\n
Base64: A group of binary-to-text encoding schemes that represent binary data in an ASCII string format by translating it into a radix-64 representation. The term “Base64” originates from a specific MIME content transfer encoding. Each Base64 digit represents exactly 6 bits of data. Three 8-bit bytes (i.e., 24 bits) can therefore be represented by four 6-bit Base64 digits. Common to all binary-to-text encoding schemes, Base64 is designed to carry data stored in binary formats across channels that only reliably support text content. Base64 is particularly prevalent on the World Wide Web where its uses include the ability to embed image files or other binary assets inside textual assets such as HTML and CSS files. †\n
Baseline: In European and West Asian typography and penmanship, the line upon which most letters “sit” and below which descenders extend. †\n
Bash: A Unix shell and command language written by Brian Fox for the GNU Project as a free software replacement for the Bourne shell. First released in 1989, Bash has been used widely as the default login shell for most Linux distributions and Apple’s macOS Mojave and earlier versions. †\n
Basic access authentication: A method for an HTTP user agent (e.g., a web browser) to provide a user and password when making a request. In basic HTTP authentication, a request contains a header field in the form of Authorization: Basic <credentials>, where “credentials” is the Base64 encoding of ID and password joined by a single colon (“:”). Basic access authentication is specified in RFC 7617 from 2015, which obsoletes RFC 2617 from 1999. †\n
Basic Multilingual Plane: The first Unicode plane, plane 0, containing characters for almost all modern languages, and a large number of symbols. A primary objective for the BMP is to support the unification of prior character sets as well as characters for writing. Most of the assigned code points in the BMP are used to encode Chinese, Japanese, and Korean (CJK) characters. †\n
BBCode: A lightweight markup language used to format posts in many message boards. The available tags are usually indicated by square brackets ([]) surrounding a keyword, and parsed by the message board system before being translated into a markup language that web browsers understand, like HTML. †\n
BDD: → Behavior-Driven Development
Behavior: In web development, the code that deals with how content can be interacted with. This is often achieved through JavaScript.
Behavior-Driven Development: An agile software development process that encourages collaboration among developers, QA, and non-technical or business participants in a software project. BDD encourages teams to use conversation and concrete examples to formalize a shared understanding of how the application should behave. It emerged from Test-Driven Development (TDD). BDD combines the general techniques and principles of TDD with ideas from domain-driven design and object-oriented analysis and design to provide software development and management teams with shared tools and a shared process to collaborate on software development. †\n
Below the fold: The part of a web page that is visible only after scrolling down.
BEM: → Block Element Modifier
Best practice: A method or technique that has been generally accepted as superior to any alternatives because it produces results that are superior to those achieved by other means or because it has become a standard way of doing things, e.g., a standard way of complying with legal or ethical requirements. Best practices are used to maintain quality as an alternative to mandatory legislated standards. †\n
Bézier curve: A parametric curve, mathematically based on Bernstein polynomials, that is defined by a set of control points P₀ through P_n, where n is called its order, and where the first and last points are always the end points of the curve, and where intermediate control points (if any) generally do not lie on the curve. Named after Pierre Bézier (1910–1999). †\n
Bfcache: → Back/forward cache
BFF: → Backend for Frontend
BGP: → Border Gateway Protocol
BHO: → Browser Helper Object
Bidi: → Bidirectional
Bidirectional: Text that contains both text directionalities, right-to-left (RTL or dextrosinistral) and left-to-right (LTR or sinistrodextral), and which generally involves text containing different types of alphabets. †\n
Big Bang: The practice of releasing a great amount of working software all at one time, as opposed to incrementally.
Big integer: An integral data type of 64 bits, with a signed range from –9,223,372,036,854,775,808 to 9,223,372,036,854,775,807, and an unsigned range from 0 to 18,446,744,073,709,551,615.
Big O notation: A mathematical notation that describes the limiting behavior of a function when the argument tends towards a particular value or infinity. It is a member of a family of notations invented by Paul Bachmann, Edmund Landau, and others, collectively called Bachmann-Landau notation or asymptotic notation. In computer science, big O notation is used to classify algorithms according to how their running time or space requirements grow as the input size grows. In analytic number theory, big O notation is often used to express a bound on the difference between an arithmetical function and a better understood approximation. †\n
Binary chop: → Binary search algorithm
Binary large object: A collection of binary data stored as a single entity. Blobs are typically images, audio, or other multimedia objects, though sometimes binary executable code is stored as a blob. †\n
Binary number: A number expressed in the base-2 numeral system or binary numeral system, which uses only two symbols: typically “0” (zero) and “1” (one). †\n
Binary search algorithm: A search algorithm that finds the position of a target value within a sorted array. Binary search compares the target value to the middle element of the array. If they are not equal, the half in which the target cannot lie is eliminated and the search continues on the remaining half, again taking the middle element to compare to the target value, and repeating this until the target value is found. If the search ends with the remaining half being empty, the target is not in the array. †\n
Binding: The association of entities (data or code) with identifiers. An identifier bound to an object is said to reference that object. Machine languages have no built-in notion of identifiers, but name-object bindings as a service and notation for the programmer is implemented by programming languages. Binding is intimately connected with scoping, as scope determines which names bind to which objects—at which locations in the program code (lexically) and in which one of the possible execution paths (temporally). †\n
Bitbucket: A Git-based source code repository hosting service owned by Atlassian. Bitbucket was launched in 2008. † ℹ︎ bitbucket.org\n
Bitmap: A raster graphics image file format used to store bitmap digital images, independently of the display device (such as a graphics adapter). Also known as bitmap image file or device independent bitmap (DIB) file format. †\n; → Raster image
BITV: → Barrierefreie-Informationstechnik-Verordnung
Black hat: Someone who violates computer security or systems for personal gain or maliciousness. †\n
Black Mode: → Dark Mode
Black-box testing: A method of software testing that examines the functionality of an application without peering into its internal structures or workings. This method of test can be applied virtually to every level of software testing: unit, integration, system, and acceptance. Black-box testing is sometimes referred to as specification-based testing. †\n
Blacklist: A basic access control mechanism that allows through all elements (email addresses, users, passwords, URLs, IP addresses, domain names, file hashes, etc.), except those explicitly mentioned. Those items on the list are denied access. The opposite of a blacklist is a whitelist. †\n
Blink: A browser engine used in the Chrome web browser and other projects. It is developed as part of the Chromium project with contributions from Google, Facebook, Microsoft, Opera, Adobe, Intel, IBM, Samsung, and others. Blink was released in 2013. †\n
Blisk: A developer-centered cross-platform web browser. Blisk was first released in 2016. ℹ︎ blisk.io\n
Blob: In JavaScript, an object that represents a blob, which is a file-like object of immutable, raw data. Blobs can be read as text or binary data, or converted into a ReadableStream so its methods can be used for processing the data. Blobs can represent data that is not necessarily in a JavaScript-native format. ‡\n; → Binary large object
Block: In CSS, a section enclosed by an opening ({) and a closing curly brace (}).; In JavaScript, a collection of related statements enclosed by an opening ({) and a closing curly brace (}). ‡\n; → Block box; → Block container box; → Block container element; → Block-level box; → Block-level element
Block box: A block-level box that is also a block container.
Block container: → Block container element
Block container box: A block-level box that is not a table box or the principal box of a replaced element. It either contains only block-level boxes or, if establishing an inline formatting context, only inline-level boxes.
Block container element: An element whose principal box is a block container box.
Block element: → Block-level element
Block Element Modifier: A naming convention for HTML and CSS classes. BEM was introduced in 2005 by Yandex. ℹ︎ getbem.com\n
Block flow: A CSS concept referring to the direction in which blocks are running. In an English document, block flow goes from top to bottom.
Block formatting context: A formatting context in which boxes are laid out vertically. Vertical margins are respected but collapse.
Block-level box: A box created by a block-level element.
Block-level element: An element that is formatted visually as a block.
Blog: A discussion or informational website published on the World Wide Web consisting of discrete, often informal diary-style text entries (posts). Posts are typically displayed in reverse chronological order, so that the most recent post appears first, at the top of the web page. Until 2009, blogs were usually the work of a single individual, occasionally of a small group, and often covered a single subject or topic. In the 2010s, “multi-author blogs” (MABs) emerged. †\n
Blogging: The act of running a blog, and writing posts for a blog.
Blogosphere: A collective term for all blogs and their interconnections. The term implies that blogs exist together as a connected community (or as a collection of connected communities) or as a social networking service in which everyday authors can publish their opinions. †\n
BMP: → Basic Multilingual Plane; → Bitmap
BOM: → Byte Order Mark
Bookmark: A URI that is stored for later retrieval in any of various storage formats. All modern web browsers include bookmark features. Bookmarks are normally accessed through a menu in the user’s web browser, and folders are commonly used for organization. †\n
Bookmark icon: → Favicon
Bookmarklet: Unobtrusive JavaScript stored as the URL of a bookmark in a web browser or as a hyperlink on a web page. Bookmarklets allow to add one-click functionality to the respective browser or web page. †\n
Boolean: A data type that has one of two possible values (usually denoted true and false) which is intended to represent the two truth values of logic and Boolean algebra. It is named after George Boole, who first defined an algebraic system of logic in the mid-19th century. The Boolean data type is primarily associated with conditional statements. †\n
Bootstrap: An HTML/CSS framework. ℹ︎ getbootstrap.com\n
Border: Per the CSS box model, any kind of line (solid, dotted, dashed, etc.) surrounding an element of a document, if present. The border area lies between the padding and margin areas of a box.
Border Gateway Protocol: A standardized exterior gateway protocol designed to exchange routing and reachability information among autonomous systems on the Internet. BGP is classified as a path-vector routing protocol, and it makes routing decisions based on paths, network policies, or rule sets configured by a network administrator. It was first described in 1989 in RFC 1105, and has been in use on the Internet since 1994. †\n
Bottom-posting: A posting style in which the reply follows the quote. †\n
Bounce rate: A marketing term used in web traffic analysis that represents the percentage of visitors who enter a site and then leave (“bounce”) rather than continue to view other pages within the same site. The bounce rate is calculated by counting the number of single page visits and dividing that by the total visits. It is then represented as a percentage of total visits. †\n
Bound variable: A variable that was previously free, but has been bound to a specific value or set of values. †\n
Boundary value problem: A boundary value problem is a differential equation together with a set of additional constraints, called the boundary conditions. A solution to a boundary value problem is a solution to the differential equation which also satisfies the boundary conditions. †\n
Bounding box: The smallest possible rectangle (aligned with the axes of that element’s user coordinate system) that entirely encloses an element and its descendants. ‡\n
Bourne shell: A shell, or command-line interpreter, for computer operating systems. Developed by Stephen Bourne at Bell Labs, it was a replacement for the Thompson shell, whose executable file had the same name (sh). The Bourne shell was released in 1979 in the Version 7 Unix release distributed to colleges and universities. †\n
Bower: A maintenance-only package manager for the JavaScript programming language. Bower was first released in 2012. ℹ︎ bower.io\n
Box: The visual space occupied by an HTML element’s content. †\n
Box model: A concept for the rectangular boxes that are generated for elements in the document tree and laid out according to the visual formatting model. The boxes consist of content, padding, border, and margin areas.
Box model hack: A popular early 2000’s workaround for Internet Explorer 5/5.5’s incorrect support of the CSS box model. The box model hack was obsoleted by improved browser implementations and an additional CSS property (box-sizing). ℹ︎ is.gd/nZKbJw\n
Boy Scout Rule: The idea to “always leave code better than you found it,” which may be attributable to Robert C. Martin.
Bracket notation: One of two ways to access object properties in JavaScript (objectName['propertyName']), the other being dot notation.
Braille (⠃⠗⠁⠊⠇⠇⠑): A tactile writing system used by people who are visually impaired. Braille is traditionally written with embossed paper. Braille users can read computer screens and other electronic supports using refreshable braille displays. They can write braille with the original slate and stylus or type it on a braille writer, such as a portable braille notetaker or computer that prints with a braille embosser. Braille was developed in 1824 by Louis Braille, who published it in 1829. †\n
Branch: A duplicate of an object under version control. Branches are also known as trees, streams, or codelines. The originating branch is sometimes called the parent branch, the upstream branch (or “upstream,” especially if the branches are maintained by different organizations or individuals), or the backing stream. Child branches are branches that have a parent; a branch without a parent is referred to as the trunk or the mainline. †\n
Branch predication: → Predication
Branching: The duplication of an object under version control (such as a source code file or a directory tree) so that modifications can occur in parallel along multiple branches. Branching generally implies the ability to later merge or integrate changes back onto the parent branch. †\n
BREAD: → Browse, Read, Edit, Add, Delete
Breadcrumb: A graphical control element frequently used as a navigational aid in user interfaces and on web pages. It allows users to keep track and maintain awareness of their locations within programs, documents, or websites. †\n
Breakpoint: In software development, an intentional stopping or pausing place in a program, put in place for debugging purposes. A breakpoint is sometimes also referred to as a pause. †\n; In web development, any point at which a media query is introduced and the layout changed. ‡\n
Brewer’s Theorem: → CAP Theorem
Bring Your Own License: A licensing model that allows to use available software licenses flexibly, both on-premise and in the cloud. While BYOL can help to save licensing cost, it comes with the responsibility of managing the respective licenses.
Broken link: A hyperlink that does not work, or work anymore, that is, that points to a target that is not available. Broken links constitute link rot.
Brotli: A data format specification for data streams compressed with a specific combination of the general-purpose LZ77 lossless compression algorithm, Huffman coding, and second-order context modeling. † ℹ︎ github.com/google/brotli\n
Browse, Read, Edit, Add, Delete: A variation of CRUD. †\n
Browser: A software application for accessing information on the World Wide Web. When a user requests a particular website, the web browser retrieves the necessary content from a web server and displays the resulting web page on the user’s device. As of March 2019, more than 4.3 billion people use a browser, which is about 55% of the world’s population. The three most popular browsers are Chrome, Firefox, and Safari. †\n
Browser detection: → Browser sniffing
Browser engine: A core software component of every major web browser. The primary job of a browser engine is to transform HTML documents and other resources of a web page into an interactive visual representation on a user’s device. Besides “browser engine,” two other terms are in common use regarding related concepts: “layout engine” and “rendering engine.” In theory, layout and rendering (or “painting”) could be handled by separate engines. In practice, however, they are tightly coupled and rarely considered separately. †\n
Browser extension: A small software module for customizing a web browser. Browsers typically allow a variety of extensions, including user interface modifications, ad blocking, and cookie management. Browser plugins are a separate type of module. The main difference is that extensions are usually just source code, but plugins are always executables (i.e., object code). As of 2019, plugins have been deprecated by most browsers, while extensions are widely used. †\n
Browser Helper Object: A DLL module designed as a plugin for Microsoft’s Internet Explorer web browser to provide added functionality. BHOs were introduced in 1997 with the release of Internet Explorer 4. Most BHOs are loaded once by each new instance of Internet Explorer. BHOs are still supported as of Windows 10, through Internet Explorer 11, while BHOs are not supported in Edge. †\n
Browser sniffing: A set of techniques used in websites and web applications in order to determine the web browser a visitor is using, and to serve browser-appropriate content to the visitor. This practice is sometimes used to circumvent incompatibilities between browsers due to misinterpretation of HTML, Cascading Style Sheets (CSS), or the Document Object Model (DOM). While the World Wide Web Consortium (W3C) maintains up-to-date central versions of some of the most important Web standards in the form of recommendations, in practice no vendor has developed a browser which adheres exactly to these standards. As a result, different browsers may display the same page differently, and browser sniffing was developed to detect the web browser in order to help ensure consistent display of content. †\n
Browser testing: The testing of websites and apps in different web browsers.
Browser War: A market competition between web browsers, usually referring to the First Browser War (1995–2001) between Internet Explorer (Microsoft) and Navigator (Netscape) or the Second Browser War (2004–2017) between Internet Explorer, Firefox (Mozilla), and Chrome (Google).
Browsing: A kind of orienting strategy to identify something of relevance. One of the two major ways of interacting with the Web, the other one being searching. †\n
Browsing context: The environment in which a browser displays a document, as with a tab, window, or frame. Each browsing context has a specific origin, the origin of the active document, and a history that lists all the displayed documents in order. Communication between browsing contexts is restricted. ‡\n
Buffer: A storage in physical memory used to temporarily store data while it is being transferred from one place to another. ‡\n
Bug: An error, flaw, or fault in a computer program or system that causes it to produce an incorrect or unexpected result, or to behave in unintended ways. Most bugs arise from mistakes and errors made in either a program’s source code or its design. †\n
Bug tracking system: A software application that keeps track of reported software bugs in software development projects. It may be regarded as a type of issue tracking system. Many bug tracking systems allow end users to enter bug reports directly. Other systems are used only internally in a company or organization doing software development. Typically, bug tracking systems are integrated with other project management software. A bug tracking system is usually a necessary component of a professional software development infrastructure. †\n
Bugfix: → Patch
Bugzilla: A web-based general-purpose bug tracking system and testing tool originally developed and used by the Mozilla project. Bugzilla was first released in 1998 by Netscape. † ℹ︎ bugzilla.org\n
Build Verification Test: → Smoke testing
Bulletin Board Code: → BBCode
Bundling: The process of dynamically or statically merging (bundling) several files, notably JavaScript modules, for output to a client or a server. Bundling reduces the number of files and requests to be delivered to a client and thus helps improve performance.
Bushnell’s Law: An aphorism attributed to Atari founder Nolan Bushnell, on the subject of video game design: “All the best games are easy to learn and difficult to master. They should reward the first quarter and the hundredth.” This is also referred to with the sentence “easy to learn, hard to master.” †\n
BVT: → Build Verification Test
BYOL: → Bring Your Own License
Byte Order Mark: A particular use of a special Unicode character, U+FEFF BYTE ORDER MARK, whose appearance as a magic number at the start of a text stream can signal several things to a program reading the text: the byte order, or endianness, of the text stream in the cases of 16-bit and 32-bit encodings; the fact that the text stream’s encoding is Unicode, to a high level of confidence; or which Unicode character encoding is used. †\n
Bytecode: A form of instruction set designed for efficient execution by a software interpreter. Unlike human-readable source code, bytecodes are compact numeric codes, constants, and references (normally numeric addresses) that encode the result of compiler parsing and performing semantic analysis of things like type, scope, and nesting depths of program objects. The name “bytecode” stems from instruction sets that have one-byte opcodes followed by optional parameters. †\n

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CA: → Certificate Authority; → Confidentiality Agreement
Cache: A hardware or software component that stores data so that future requests for that data can be served faster. The data stored in a cache might be the result of an earlier computation or a copy of data stored elsewhere. A cache hit occurs when the requested data can be found in a cache, while a cache miss occurs when it cannot. Cache hits are served by reading data from the cache, which is faster than recomputing a result or reading from a slower data store. †\n
Cache busting: A type of HTTP flood attack that uses query variations to get around caching. Instead of returning results from the cache, other servers must be contacted which increases their load to potentially overwhelm them.
Cache eviction: The automatically or manually requested removal of old, unused, or large data from a cache.
Cache partitioning: The dividing and assigning of cache space to different system or application tasks, in order to improve security (as with browser cache partitioning) or performance.
Cache poisoning: → DNS spoofing
California Consumer Privacy Act: A state statute intended to enhance privacy rights and consumer protection for residents of California, United States. The bill was passed in 2018, amending the California Civil Code. The intentions of the CCPA are to provide California residents with the right to know what personal data is being collected about them; to know whether their personal data is sold or disclosed and to whom; to say “no” to the sale of personal data; to access their personal data; to request a business to delete personal information about a consumer collected from that consumer; and not to be discriminated against for exercising their privacy rights. †\n
Call stack: A mechanism for an interpreter (like the JavaScript interpreter in a web browser) to keep track of its place in a script that calls multiple functions—what function is currently being run and what functions are called from within that function, etc. ‡\n
Call to Action: A marketing term used extensively in advertising and selling. It refers to any device designed to prompt an immediate response or encourage an immediate sale. A CTA most often refers to the use of words or phrases that can be incorporated into sales scripts, advertising messages or web pages that encourage consumers to take prompt action. †\n
Callback: Executable code that is provided as an argument to other code that executes—calls back—that argument immediately (synchronous callback) or at a later time (asynchronous callback). †\n
Callback queue: A queue of messages (functions) that are processed in a “first in, first out” order (FIFO) by the JavaScript event loop.
Camel case: The practice of writing phrases such that each word or abbreviation in the middle of the phrase begins with a capital letter, with no intervening spaces or punctuation. Common examples include “iPhone” and “eBay.” Camel case is also sometimes used in online usernames such as “johnSmith.” In programming, camel case is often used for variable names. †\n
Camino: A discontinued GUI-based web browser based on Mozilla’s Gecko layout engine, specifically designed for the OS X operating system. In place of an XUL-based user interface used by most Mozilla-based applications, Camino used Mac-native Cocoa APIs. In 2013, the Camino Project stopped the development of the browser. †\n
Canary: Software that is only released to a small group of users, making it easy to roll it back in case of serious defects. The name comes from canaries that were once used in coal mines to warn of dangerous levels of carbon monoxide.
Candidate Recommendation: The specification-testing phase of a World Wide Web Consortium (W3C) specification (also known as a recommendation).
Canonical equivalence: The assuming of code point sequences to have the same appearance and meaning when printed or displayed. †\n
Canonical link: An HTML element marked rel=canonical that helps webmasters prevent duplicate content issues in search engine optimization by specifying the “canonical” or “preferred” version of a web page. †\n
Canonical Name: A type of resource record in the Domain Name System (DNS) which maps one domain name (an alias) to another (the canonical name). †\n
Canvas: A container, the HTML canvas element, that allows for dynamic, scriptable rendering of 2D and 3D shapes and bitmap images by providing an empty graphic zone on which specific JavaScript APIs can draw (such as Canvas 2D or WebGL). ‡\n
CAP Theorem: A theoretical computer science theorem that states that it is impossible for a distributed data store to simultaneously provide more than two out of the following three guarantees: 1) Consistency: Every read receives the most recent write or an error. 2) Availability: Every request receives a (non-error) response, without the guarantee that it contains the most recent write. 3) Partition tolerance: The system continues to operate despite an arbitrary number of messages being dropped (or delayed) by the network between nodes. The CAP Theorem implies that in the presence of a network partition, one has to choose between consistency and availability. †\n
CAPTCHA: A type of challenge–response test used in computing to determine whether the user is human. The term stands for “completely automated public Turing test to tell computers and humans apart” and was coined in 2003 by Luis von Ahn, Manuel Blum, Nicholas J. Hopper, and John Langford. †\n
Card sorting: A method that aids the design or evaluation of the information architecture of a website. Card sorting is usually performed with groups, with attendees organizing topics into categories or folksonomies.
Caret: A grapheme—“^”, “‸”, “⁁”, or “＾”—with several uses, including as a proofreading mark, as a special character in programming languages, as an escape character, or for estimation. †\n
Carousel: A slideshow-like design element for web pages. A carousel allows focus on one unit of content and media while providing access to similar units (by some way of carousel navigation).
Cascade: The order by which declarations are applied in CSS: 1) per target media type; 2) per importance and origin (from user agent to important user declarations); 3) by specificity; and 4) by order in which the declaration was specified (with all having the same weight, origin, and specificity, the latest declaration prevails).
Cascading HTML Style Sheets: A style sheet language proposal drafted in 1994 by Håkon Wium Lie. ℹ︎ w3.org/People/howcome/p/cascade\n
Cascading Style Sheets: A style sheet language that allows to manage the presentation of markup languages like HTML or XML. The first final specification of CSS was published in 1996 by Håkon Wium Lie and Bert Bos. ℹ︎ w3.org/Style/CSS\n
Case: In engineering, as use case, a list of actions or event steps typically defining the interactions between a role (known in UML as an actor) and a system to achieve a goal. The actor can be a human or other external system. In systems engineering, use cases are used at a higher level than within software engineering, often representing missions or stakeholder goals. †\n; In programming, a selection mechanism to allow a variable to change the flow of a program. †\n; In typography, as letter case, the distinction between the letters that are in larger upper case (also uppercase, capital letters, capitals, caps, large letters, or more formally majuscule) and smaller lower case (also lowercase, small letters, or more formally minuscule) in the written representation of certain languages. †\n
catch: → try…catch\n
CBD: → Component-Based Development
CBSE: → Component-Based Software Engineering
CC/PP: → Composite Capability/Preference Profiles
CCPA: → California Consumer Privacy Act
CCT: → Chrome Custom Tabs
ccTLD: → Country code top-level domain
CD: → Corporate Design; → Continuous Delivery; → Continuous Deployment
CDATA: → Character Data
CDN: → Content Delivery Network
CDP: → Chrome DevTools Protocol
CERT: A certificate resource record in the Domain Name System (DNS). †\n
Certificate: An electronic document used to prove the ownership of a public key. The certificate includes information about the key, information about the identity of its owner (called the subject), and the digital signature of an entity that has verified the certificate’s contents (called the issuer). †\n
Certificate Authority: An entity that issues digital certificates. A digital certificate certifies the ownership of a public key by the named subject of the certificate. This allows others to rely upon signatures or on assertions made about the private key that corresponds to the certified public key. A CA acts as a trusted third party, trusted both by the subject (owner) of the certificate and by the party relying upon the certificate. The format of these certificates is specified by the X.509 standard. One particularly common use for certificate authorities is to sign certificates used in HTTPS, the secure browsing protocol for the World Wide Web. †\n
CES: → Customer Effort Score
CFML: → ColdFusion Markup Language
CGI: → Common Gateway Interface
Chaining: The calling of several methods after another on an object.
Change list: The set of changes made in a single commit. This can also represent a sequential view of the source code, allowing the examination of source as of any particular changelist ID. †\n
Change set: → Change list
Changeset: A method to handle multi-package changes and versions. ℹ︎ github.com/atlassian/changesets\n
Channel messaging: An API described by the HTML specification that enables independent pieces of code (e.g., scripts in different browsing contexts) to communicate directly. Channel messaging works through two-way channels (or pipes) with a port at each end. ‡\n
Chaos engineering: The discipline of experimenting on a software system in production in order to build confidence in the system’s capability to withstand turbulent and unexpected conditions. Chaos engineering can be used to achieve resilience against infrastructure, network, and application failures. †\n
Character: An encoded symbol that maps to a glyph.
Character Data: A concept used for distinct but related purposes in the markup languages SGML and XML. “CDATA” indicates that a certain portion of the document is general character data, rather than non-character data or character data with a more specific, limited structure. †\n
Character encoding: A mapping of code points to characters, like UTF-8.
Character entity reference: A character reference that refers to a character by the name of an entity which has the desired character as its replacement text. The entity must either be predefined (built into the markup language) or explicitly declared in a document type definition (DTD). The format is the same as for any entity reference: &name;, where “name” is the case-sensitive name of the entity. †\n
Character reference: → Character entity reference; → Numeric character reference
Character set: → Character encoding
Charset: → Character encoding
CheiRank: An eigenvector with a maximal real eigenvalue of the Google matrix G^* constructed for a directed network with the inverted directions of links. CheiRank is similar to the PageRank vector, which ranks the network nodes in average proportionally to a number of incoming links being the maximal eigenvector of the Google matrix G with a given initial direction of links. Due to inversion of link directions the CheiRank ranks the network nodes in average proportionally to a number of outgoing links. †\n
Chrome: A cross-platform web browser, based on the Chromium browser project. Chrome was released in 2008 by Google. ℹ︎ google.com/chrome\n; The graphical elements of a web browser, like title, address, and status bar as well as navigation elements.
Chrome Custom Tabs: A Chrome feature that allows native apps to invoke the Chrome browser with customized actions, toolbars, and animations.
Chrome DevTools: A set of web developer tools built directly into the Chrome web browser. ℹ︎ is.gd/TsOXbb\n
Chrome DevTools Protocol: A protocol to “instrument, inspect, debug, and profile” Chromium, Chrome, and other Blink-based browsers. ℹ︎ is.gd/a55qQ3\n
Chrome OS: A Linux kernel-based operating system designed by Google. Chrome OS is derived from the free software Chromium OS and uses the Google Chrome web browser as its principal user interface. Google announced Chrome OS in 2009, conceiving it as an operating system in which both applications and user data reside in the cloud—hence Chrome OS primarily runs web applications. Chrome OS is only available pre-installed on hardware from Google manufacturing partners, but there are unofficial methods that allow it to be installed in other equipment. † ℹ︎ google.com/chromebook/chrome-os\n
ChromeVox: A screen reader for Chrome OS as well as the Chrome web browser developed by Google. ℹ︎ chromevox.com\n
Chromium: A Google-developed project whose source code can be compiled into a web browser. Google’s Chrome browser is based on the Chromium code, as are several other browsers, including Edge, Opera, and Silk. Other parties have compiled the code as-is, releasing their browsers under the Chromium name. † ℹ︎ chromium.org\n
CHSS: → Cascading HTML Style Sheets
CI: → Continuous Integration; → Corporate Identity
CIDR: → Classless Inter-Domain Routing
Cipher: An algorithm for encryption or decryption. To encipher or encode is to convert information into cipher or code. †\n
CircleCI: A continuous integration and delivery platform. CircleCI was founded in 2011. ℹ︎ circleci.com\n
CL: → Change list
Class: An extensible program code template for creating objects, providing initial values for state (member variables), and implementations of behavior (member functions or methods). In many languages, the class name is used as the name for the class (the template itself), the name for the default constructor of the class (a subroutine that creates objects), and as the type of objects generated by instantiating the class. †\n; In web development, the (value of the) class attribute, usually used as a selector for styling purposes.
Class variable: Any variable declared with the static modifier of which a single copy exists, regardless of how many instances of the class there are. †\n
Classitis: In software development, a negative outcome of the disputed goal to work with many small classes.; In web development, the excessive use of class attributes and values.
Classless Inter-Domain Routing: A method for allocating IP addresses and for IP routing. The Internet Engineering Task Force (IETF) introduced CIDR in 1993 to replace the previous classful network addressing architecture on the Internet. The goal of CIDR was to slow the growth of routing tables on routers across the Internet, and to help slow the rapid exhaustion of IPv4 addresses. †\n
Clearfix: A name for a variety of float-clearing techniques that may (when CSS-only) or may not (as with relying on presentational helper classes) meet development best practices. ℹ︎ is.gd/ywDpA3\n
CLI: → Command-Line Interface
Click: A physical or emulated interaction with a pointing device.
Click-through rate: The ratio of users who click on a specific link to the number of total users who view a page, email, or advertisement. It is commonly used to measure the success of an online advertising campaign for a particular website as well as the effectiveness of email campaigns. †\n
Clickjacking: A malicious technique of tricking a user into clicking on something different from what the user perceives, thus potentially revealing confidential information or allowing others to take control of the user’s computer. †\n
Client: A piece of computer hardware or software that accesses a service made available by a server. The server is often (but not always) on another computer system, in which case the client accesses the service by way of a network. †\n
Client Hints: A set of HTTP request header fields for proactive content negotiation allowing clients to indicate a list of device and agent specific preferences. Client Hints enable automated delivery of optimized assets, like the automatic negotiation of image DPR resolution. ‡ ℹ︎ is.gd/NIdm5F\n
Client side: Operations on the client as opposed to the server side in a client-server relationship. †\n
Client-Side Rendering: A technique in which a page is rendered on the client side, as opposed to the server side (as with SSR). On the first request, only a skeleton (a minimal HTML document) is returned by the server. It is then populated on the client side, usually via JavaScript, to turn it into a fully rendered page.
Cloaking: A search engine optimization (SEO) technique in which the content presented to the search engine spider is different from that presented to a user’s browser. This can be done by delivering content based on the IP addresses or the User-Agent HTTP header of the user requesting the page. When a user is identified as a search engine spider, a server-side script delivers a different version of the web page, one that contains content not present on the visible page, or that is present but not searchable. The purpose of cloaking is to deceive search engines so they display the page when it would not otherwise be displayed (black hat SEO). However, it can also be a functional (though antiquated) technique for informing search engines of content they would not otherwise be able to locate. †\n
Clojure: A dynamic and functional dialect of the Lisp programming language on the Java platform. Like other Lisp dialects, Clojure treats code as data and has a Lisp macro system. The development process is community-driven, overseen by Rich Hickey as a “benevolent dictator for life” (BDFL). Clojure advocates immutability and immutable data structures and encourages programmers to be explicit about managing identity and its states. † ℹ︎ clojure.org\n
Clone detection: The automated process of finding duplication in source code. †\n
Closure: A technique for implementing lexically scoped name binding in a language with first-class functions. Operationally, a closure is a record storing a function together with an environment. The environment is a mapping associating each free variable of the function (variables that are used locally, but defined in an enclosing scope) with the value or reference to which the name was bound when the closure was created. Unlike a plain function, a closure allows the function to access those captured variables through the closure’s copies of their values or references, even when the function is invoked outside their scope. †\n
Cloud: → Cloud computing; → Cloud storage
Cloud computing: The on-demand availability of computer system resources, especially data storage and computing power, without direct active management by the user. The term is generally used to describe data centers available to many users over the Internet. Large clouds, predominant today, often have functions distributed over multiple locations from central servers. If the connection to the user is relatively close, it may be designated an edge server. †\n
Cloud storage: A model of computer data storage in which the digital data is stored in logical pools. The physical storage spans multiple servers (sometimes in multiple locations), and the physical environment is typically owned and managed by a hosting company. These cloud storage providers are responsible for keeping the data available and accessible, and the physical environment protected and running. †\n
CLS: → Cumulative Layout Shift
Cluster: A set of loosely or tightly connected computers that work together so that, in many respects, they can be viewed as a single system. Unlike grid computers, computer clusters have each node set to perform the same task, controlled and scheduled by software. †\n
CMP: → Consent Management Platform
CMS: → Content Management System
CMYK: → Cyan, Magenta, Yellow, and Key
CNAME: → Canonical Name
CNAME cloaking: The disguising of third-party resources as first-party resources through the modification of domain CNAME entries. CNAME cloaking is used to get around tracking protections.
Coalescing: The merging of two adjacent free blocks of memory, which is relevant as when an application frees memory, gaps can fall in the memory segment that the application uses. †\n; A way to provide a default value if an operand is null or undefined. This so-called null or nullish coalescing allows a default value to be defined for cases where a more specific value is not available. †\n
CoC: → Code of Conduct; → Convention over Configuration
Code: The set of instructions forming a computer program which is executed by a computer. It is one of two components of the software which runs on computer hardware, the other being the data. †\n
Code coverage: A measure used to describe the degree to which the source code of a program is executed when a particular test suite runs. A program with high test coverage, measured as a percentage, has had more of its source code executed during testing, which suggests it has a lower chance of containing undetected software bugs compared to a program with low test coverage. Many different metrics can be used to calculate test coverage; some of the most basic are the percentage of program subroutines and the percentage of program statements called during execution of the test suite. †\n
Code debt: → Technical debt
Code golf: A type of recreational computer programming competition in which participants strive to achieve the shortest possible source code that implements a certain algorithm. Playing code golf is known as “golf scripting.” Code golf tournaments may also be named with the programming language used (for example, Perl golf). †\n
Code of Conduct: A set of rules outlining the norms, rules, and responsibilities of, or proper practices for, an individual. †\n
Code point: Any of the numerical values that make up the code space for a character encoding. Many code points represent single characters but they can also have other meanings, such as for formatting. †\n
Code refactoring: → Refactoring
Code review: A software quality assurance activity in which one or several people check a program mainly by viewing and reading parts of its source code, and they do so after implementation or as an interruption of implementation. At least one of the persons must not be the code’s author. The persons performing the checking, excluding the author, are called reviewers. †\n
Code smell: Any characteristic in the source code of a program that possibly indicates a deeper problem. Determining what is and is not a code smell is subjective, and varies by language, development methodology, and developer. The term “code smell” was popularized in the late 1990s by Kent Beck. †\n
Code splitting: The splitting of code into various bundles or components which can then be loaded on demand or in parallel. While the total amount of code is the same (and perhaps even a little larger), the amount of code needed during initial load can be reduced. ‡\n
Codeline: → Branch
CodePen: An online community for testing and showcasing user-created HTML, CSS, and JavaScript code snippets. It functions as a code editor and learning environment, where developers can create code snippets, called pens, test, and share them. CodePen was founded in 2012. † ℹ︎ codepen.io\n
Coding by Convention: → Convention over Configuration
Coding guidelines: Rules for how code is to be designed and formatted. Coding guidelines are usually established in organizations with several developers and development teams.
COEP: → Cross-Origin-Embedder-Policy\n
CoffeeScript: A programming language that compiles to JavaScript. It adds syntactic sugar inspired by Ruby, Python, and Haskell in an effort to enhance JavaScript’s brevity and readability. Specific additional features include list comprehension and destructuring assignment. † ℹ︎ coffeescript.org\n
Cognitive disability: As disabilities affecting cognitive ability, a concept encompassing various intellectual or cognitive deficits, including intellectual disability (formerly called mental retardation), deficits too mild to properly qualify as intellectual disability, various specific conditions (such as specific learning disability), and problems acquired later in life through acquired brain injuries or neurodegenerative diseases like dementia. Many of these disabilities have an effect on memory, which is the ability to recall what has been learned over time. †\n
Cold data: Rarely accessed data.
ColdFusion: A commercial rapid web application development computing platform created in 1995 by J.J. Allaire. (The programming language used with the platform is also commonly called ColdFusion, though is more accurately known as CFML.) ColdFusion was originally designed to make it easier to connect simple HTML pages to a database. By version 2 (1996), it became a full platform that included an IDE in addition to a full scripting language. † ℹ︎ is.gd/r6E53v\n
ColdFusion Markup Language: A scripting language for web development that runs on the Java virtual machine, the .NET framework, and Google App Engine. Multiple implementations of CFML engines are available, including Adobe ColdFusion, Lucee, New Atlanta BlueDragon, Railo, and Open BlueDragon. †\n
Collapsed margin: → Margin collapsing
Color blindness: The decreased ability to see color or differences in color. 8% of men and 0.5% of women have some form of color blindness. The most common forms of color blindness are deuteranomaly, deuteranopia, protanomaly, and protanopia. †\n
Color circle: → Color wheel
Color management: The controlled conversion between the color representations of various devices, such as image scanners, digital cameras, monitors, TV screens, film printers, computer printers, offset presses, and corresponding media. The primary goal of color management is to obtain a good match across color devices; for example, the colors of one frame of a video should appear the same on a computer LCD monitor, on a plasma TV screen, and as a printed poster. Color management helps to achieve the same appearance on all of these devices, provided the devices are capable of delivering the needed color intensities. Color management cannot guarantee identical color reproduction, as this is rarely possible, but it can at least give more control over any changes which may occur. †\n
Color scheme: The choice of colors used in design to create style and appeal. Colors that create an aesthetic feeling when used together will commonly accompany each other in color schemes. †\n
Color wheel: An abstract illustrative organization of color hues around a circle, which shows the relationships between primary colors, secondary colors, tertiary colors, etc. Some sources use the terms “color wheel” and “color circle” interchangeably; however, one term or the other may be more prevalent in certain fields. †\n
Comma-Separated Values: As a CSV file, a delimited text file that uses a comma to separate values. Each line of the file is a data record. Each record consists of one or more fields, separated by commas. The use of the comma as a field separator is the source of the name for this file format. A CSV file typically stores tabular data (numbers and text) in plain-text, in which case each line will have the same number of fields. The CSV file format is not fully standardized. †\n
Command: A directive to a computer program to perform a specific task. It may be issued via a command-line interface, such as a shell, or as input to a network service as part of a network protocol, or as an event in a graphical user interface triggered by the user selecting an option in a menu. †\n
Command-Line Interface: An interface processing commands to a computer program in the form of lines of text. Operating systems implement command-line interfaces in a shell for interactive access to operating system functions or services. †\n
Command-Query Separation: A principle of imperative computer programming. CQS was devised by Bertrand Meyer as part of his pioneering work on the Eiffel programming language. The principle states that every method should either be a command that performs an action, or a query that returns data to the caller, but not both. In other words, “Asking a question should not change the answer.” More formally, methods should return a value only if they are referentially transparent and hence possess no side effects. †\n
Comment: A developer-readable explanation or annotation in the source code of a computer program. Comments are added with the purpose of making the source code easier for humans to understand, and are generally ignored by compilers and interpreters. The syntax of comments in various programming languages varies considerably. †\n
Common Gateway Interface: An interface specification for web servers to execute programs that execute like console applications (also called command-line interface programs) running on a server that generates web pages dynamically. Such programs are known as CGI scripts, or simply as CGIs. The specifics of how the script is executed by the server are determined by the server. In the common case, a CGI script executes at the time a request is made and generates HTML. †\n
Common Vulnerabilities and Exposures: A system that provides a reference method for publicly known information security vulnerabilities and exposures. The United States’ National Cybersecurity FFRDC, operated by The Mitre Corporation, maintains the system, with funding from the US National Cyber Security Division of the US Department of Homeland Security. The CVE system was officially launched for the public in 1999. † ℹ︎ cve.mitre.org\n
Common Vulnerability Scoring System: An industry standard for assessing the severity of computer system security vulnerabilities. CVSS assigns severity scores to vulnerabilities, allowing responders to prioritize responses and resources according to threat. Scores are calculated based on a formula that depends on several metrics that approximate the ease and impact of an exploit. Scores range from 0 to 10, with 10 being the most severe. CVSS version 1 (CVSSv1) was released in 2005. † ℹ︎ first.org/cvss\n
CommonJS: A discontinued project with the goal to establish conventions on a module ecosystem for JavaScript outside of the web browser. The primary reason for its creation was a major lack of commonly accepted form of JavaScript scripts module units which could be reusable in environments different from that provided by a conventional web browser. CommonJS maintains specifications (including drafts) and a list of implementations. Work on CommonJS started in 2009, and ended in 2014. †\n
CommonMark: A plain-text format compatible with Markdown. CommonMark was started as a standardization effort in 2012. ℹ︎ commonmark.org\n
Community of Practice: A group of people who share a craft or a profession. The concept was first proposed in 1991 by Jean Lave and Etienne Wenger. A CoP can evolve naturally because of the members’ common interest in a particular domain or area, or it can be created deliberately with the goal of gaining knowledge related to a specific field. It is through the process of sharing information and experiences with the group that members learn from each other, and have an opportunity to develop personally and professionally. CoPs can exist in physical settings, for example, a lunchroom at work, a field setting, a factory floor, or elsewhere in the environment, but members of CoPs do not have to be co-located. †\n
Compared to what?: A question data graphics must be able to answer, according to distinguished information design expert Erward Tufte.
Compass: A CSS authoring framework. ℹ︎ compass-style.org\n
Compatibility: The ability of software to run on a particular architecture or operating system, and the ability of hardware to work with a particular CPU architecture, bus, motherboard, or operating system. Compatible software and hardware may not always run at its highest stated performance. †\n
Compatibility equivalence: The assuming of code point sequences to have possibly distinct appearances, but the same meaning in some contexts. †\n
Compatibility mode: A software mechanism in which a software either emulates an older version of software, or mimics another operating system in order to allow older or incompatible software or files to remain compatible with the computer’s newer hardware or software. Examples of software using this mode are operating systems and Internet Explorer. †\n
Compiler: A computer program that translates computer code written in one programming language (the source language) into another language (the target language). The name “compiler” is primarily used for programs that translate source code from a high-level programming language to a lower level language (e.g., assembly language, object code, or machine code) to create an executable program. †\n
Compiling: The translating of computer code written in one programming language into another language. †\n
Complementary colors: Pairs of colors which, when combined or mixed, cancel each other out (lose hue) by producing a grayscale color like white or black. When placed next to each other, they create the strongest contrast for those two colors. Complementary colors may also be called opposite colors. Modern color theory uses either the RGB additive color model or the CMY subtractive color model, and in these, the complementary pairs are red-cyan, green-magenta, and blue-yellow. In the traditional RYB color model, the complementary color pairs are red-green, yellow-purple, and blue-orange. Opponent process theory suggests that the most contrasting color pairs are red-green and blue-yellow. †\n
Component: A software package, a web service, a web resource, or a module that encapsulates a set of related functions or data. All system processes are placed into separate components so that all of the data and functions inside each component are semantically related (just as with the contents of classes). Because of this principle, it is often said that components are modular and cohesive. †\n
Component library: → Pattern library
Component-Based Development: → Component-Based Software Engineering
Component-Based Software Engineering: A branch of software engineering that emphasizes the separation of concerns with respect to the wide-ranging functionality available throughout a given software system. It is a reuse-based approach to defining, implementing, and composing loosely coupled independent components into systems. †\n
Composite Capability/Preference Profiles: A specification for defining capabilities and preferences of user agents, establishing a delivery context that can be used to guide the process of tailoring content. CC/PP is a vocabulary extension of the Resource Description Framework (RDF). † ℹ︎ w3.org/TR/CCPP-struct-vocab2\n
Compression: The process of encoding information using fewer bits than the original representation. Any particular compression is either lossy or lossless. Lossless compression reduces bits by identifying and eliminating statistical redundancy. No information is lost in lossless compression. Lossy compression reduces bits by removing unnecessary or less important information. Typically, a device that performs data compression is referred to as an encoder, and one that performs the reversal of the process (decompression) as a decoder. †\n
Computer programming: → Programming
Concurrency: The ability of different parts or units of a program, algorithm, or problem to be executed out-of-order or in partial order, without affecting the final outcome. This allows for parallel execution of the concurrent units, which can significantly improve overall speed of the execution in multi-processor and multi-core systems. †\n
Concurrent Versioning System: → Concurrent Versions System
Concurrent Versions System: A client-server version control system. CVS was developed in 1986 by Dick Grune. † ℹ︎ savannah.nongnu.org/projects/cvs\n
Conditional: A feature of a programming language which perform different computations or actions depending on whether a programmer-specified Boolean condition evaluates to true or false. Apart from the case of branch predication, this is achieved by selectively altering the control flow based on some condition. In imperative programming languages, the term “conditional statement” is usually used, whereas in functional programming, “conditional expression” or “conditional construct” are preferred. †\n
Conditional Comments: Conditional statements in HTML, interpreted by Microsoft Internet Explorer 5–9. Conditional comments can be used to provide and hide code to and from Internet Explorer. Conditional comments are no longer supported in Internet Explorer 10 and 11. †\n
Cone of Uncertainty: A model for the evolution of the amount of best case uncertainty during a project. At the beginning of a project, comparatively little is known about the product or work results, and so estimates are subject to large uncertainty. As more research and development is done, more information is learned about the project, and the uncertainty then tends to decrease. The change in uncertainty makes for the shape of a cone. †\n
Confidence testing: → Smoke testing
Confidentiality Agreement: → Non-Disclosure Agreement
Conflict of interest: A situation in which a person or organization is involved in multiple interests, financial or otherwise, and serving one interest could involve working against another. Typically, this relates to situations in which the personal interest of an individual or organization might adversely affect a duty owed to make decisions for the benefit of a third party. †\n
Connection draining: In load balancing, the allowing of existing requests (in-progress, in-flight) to complete while no new requests are being sent to the respective machine.
Consent Management Platform: A platform that requests, stores, and manages user consent. A CMP helps ensure the privacy of user data in compliance with regulation like the European Union’s GDPR or California’s CCPA/CPRA.
Consistency: In logic, a theory that does not entail a contradiction. †\n
Console: A computer program designed to be used via a text-only computer interface, such as a text terminal, the command-line interface of some operating systems (Unix, DOS, etc.), or the text-based interface included with most graphical user interface (GUI) operating systems, such as the Win32 console in Microsoft Windows, the Terminal in macOS, and xterm in Unix. A user typically interacts with a console application using only a keyboard and display screen. †\n
Constant: A value that cannot be altered by the program during normal execution, i.e., the value is constant. When associated with an identifier, a constant is said to be “named,” although the terms “constant” and “named constant” are often used interchangeably. This is contrasted with a variable. †\n
Constructor: A special type of subroutine called to create an object. It prepares the new object for use, often accepting arguments that the constructor uses to set required member variables. †\n
Container: An HTML element that contains other elements.
Containerization: An operating system paradigm in which the kernel allows the existence of multiple isolated user space instances. Such instances, called containers (Solaris, Docker), zones (Solaris), virtual private servers (OpenVZ), partitions, virtual environments (VEs), virtual kernels (DragonFly BSD), or jails (FreeBSD jail or chroot jail) may look like actual computers from the point of view of programs running in them. A computer program running on an ordinary operating system can see all resources (connected devices, files and folders, network shares, CPU power, quantifiable hardware capabilities) of that computer. However, programs running inside of a container can only see the container’s contents and devices assigned to the container. Containerization is used to securely allocate finite hardware resources among a large number of mutually-distrusting users, to consolidate server hardware by moving services on separate hosts into containers on the one server, or to separate several programs to separate containers for improved security, hardware independence, and added resource management features. †\n
Containing block: The block (element) in which a box resides.
Content: The information and experiences that are directed toward an end user or audience. Content is “something that is to be expressed through some medium, as speech, writing, or any of various arts.” Content can be delivered via many different media including the Internet, cinema, television, radio, smartphones, audio CDs, books, ebooks, magazines, and live events, such as speeches, conferences, and stage performances. †\n; → Content box
Content box: → Box
Content category: A category that HTML puts elements in. The main categories are metadata content, flow content, sectioning content, heading content, phrasing content, embedded content, and interactive content.
Content Delivery Network: A geographically distributed network of proxy servers and their data centers that has the goal to provide high availability and high performance by distributing the service spatially relative to end users. CDNs came into existence in the late 1990s as a means for alleviating performance bottlenecks of the Internet. They are a layer in the Internet ecosystem. †\n
Content Management System: A software application that can be used to manage the creation and modification of digital content. CMSs are typically used for Enterprise Content Management (ECM) and Web Content Management (WCM). ECM typically supports multiple users in a collaborative environment by integrating document management, digital asset management and record retention. Alternatively, WCM is the collaborative authoring for websites and may include text and embed graphics, photos, video, audio, maps, and program code that display content and interact with the user. †\n
Content negotiation: Server- or agent-driven mechanisms that allow to serve different versions of a document (or more generally, representations of a resource) at the same URL, so that user agents can specify which version fits their capabilities the best. Examples include requesting and receiving documents in a preferred language, or media files in a particular format. †\n
Content network: A network of websites that uses and is accessible through a particular advertising platform, that is, that can be advertised on through the respective ad platform.
Content optimization: The process of improving content, making it as interesting as possible for users and search engines, and increasing its reach.
Content Security Policy: A computer security standard introduced to prevent cross-site scripting (XSS), clickjacking, and other code injection attacks resulting from execution of malicious content in the trusted web page context. CSP provides a standard method for website owners to declare approved origins of content that browsers should be allowed to load on that website—covered types are JavaScript, CSS, HTML frames, web workers, fonts, images, embeddable objects such as Java applets, ActiveX, audio and video files, and other HTML features. † ℹ︎ w3.org/TR/CSP\n
Content sniffing: → MIME sniffing
Context switch: The process of storing the state of a process or thread, so that it can be restored and resume execution at a later point. Context switching allows multiple processes to share a single CPU, and is an essential feature of a multi-tasking operating system. The precise meaning of the phrase “context switch” varies. In the multi-tasking context, it refers to the process of storing the system state for one task, so that task can be paused and another task resumed. A context switch can also occur as the result of an interrupt, such as when a task needs to access disk storage, freeing up CPU time for other tasks. Some operating systems also require a context switch to move between user mode and kernel mode tasks. The process of context switching can have a negative impact on system performance. †\n
Continuous Delivery: A software engineering approach in which teams produce software in short cycles, ensuring that the software can be reliably released at any time and, when releasing the software, doing so manually. CD aims at building, testing, and releasing software with greater speed and frequency, and helps reduce the cost, time, and risk of delivering changes by allowing for more incremental updates to applications in production. A straightforward and repeatable deployment process is important for continuous delivery. †\n
Continuous Deployment: A software engineering approach in which software functionalities are delivered frequently through automated deployments. †\n
Continuous Integration: The practice of merging all developers’ working copies to a shared mainline (version control) several times a day. †\n
Continuous Media: Data for which there is a timing relationship between source and destination. The most common examples of continuous media are audio and motion video. Continuous media can be real-time (interactive), where there is a “tight” timing relationship between source and sink, or streaming (playback), where the relationship is less strict. ‡\n
Contrast: The difference in appearance of two or more parts of a field seen simultaneously or successively (hence: brightness contrast, lightness contrast, color contrast, simultaneous contrast, successive contrast, etc.). Visual information is always contained in some kind of visual contrast, thus contrast is an essential performance (and accessibility) feature of electronic visual displays. †\n
Control flow: The order in which individual statements, instructions, or function calls of an imperative program are executed or evaluated. †\n
Convention over Configuration: A software design paradigm used by software frameworks that attempts to decrease the number of decisions that a developer using the framework is required to make without necessarily losing flexibility. The concept was introduced by David Heinemeier Hansson to describe the philosophy of the Ruby on Rails web framework, but is related to earlier ideas like the concept of “sensible defaults” and the principle of least astonishment in user interface design. The phrase essentially means a developer only needs to specify unconventional aspects of the application. †\n
Conversion: In engineering, the converting of data from one format to another.; In marketing, the converting of visitors to customers (or to visitors who meet another conversion goal).
Conway’s Law: The adage that organizations design systems that mirror their own communication structure. Conway’s Law is named after computer programmer Melvin Conway, who introduced the idea in 1967. His original wording was: “Any organization that designs a system (defined broadly) will produce a design whose structure is a copy of the organization’s communication structure.” †\n
Cookie: A small piece of data sent from a website and stored on a user’s computer by the user’s web browser while the user is browsing. Cookies were designed to be a reliable mechanism for websites to remember stateful information or to record the user’s browsing activity. They can also be used to remember arbitrary pieces of information that the user previously entered. Cookies perform essential functions in the modern Web. Perhaps most importantly, authentication cookies are the most common method used by web servers to know whether a user is logged in or not, and which account they are logged in with. †\n
Cookie banner: A web page notification alerting and informing about the respective site’s use of cookies. Cookie banners are common on European websites because of European cookie regulations.
Cookie consent: The agreement to but also a term for the requirement for informing about the use of cookies (also known as a cookie consent form, or cookie banner).
Cookie hijacking: → Session hijacking
CoP: → Community of Practice
CORB: → Cross-Origin Read Blocking
Core Web Vitals: → Web Vitals
CORP: → Cross-Origin Resource Policy
Corporate Design: The official graphical design of the logo and name of a company or institution (or government) used on letterheads, envelopes, forms, folders, brochures, etc. †\n
Corporate Identity: The manner in which a corporation, firm, or business enterprise presents itself to the public. The corporate identity is typically visualized by branding and with the use of trademarks, but it can also include things like product design, advertising, public relations, etc. Corporate identity is a primary goal of corporate communications, in order to maintain and build the identity to accord with and facilitate the corporate business objectives. †\n
CORS: → Cross-Origin Resource Sharing
Cost-per-click: → Pay-per-click
Country code top-level domain: An Internet top-level domain generally used or reserved for a country, sovereign state, or dependent territory identified with a country code. All ASCII ccTLD identifiers are two letters long, and all two-letter top-level domains are ccTLDs. There are 312 ccTLDs in active use totally. .cn, .tk, .de and .uk contain the highest number of domains. †\n
Coupling: A state in which one object uses a function of another object. Coupling also describes the degree of interdependence between software modules, as a measure of how closely connected two routines or modules are, and the strength of the relationships between modules. Coupling is usually contrasted with cohesion. Low coupling often correlates with high cohesion, and vice versa. Low coupling is often a sign of a well-structured computer system and a good design, and when combined with high cohesion, supports the general goals of high readability and maintainability. †\n
CPA: → Critical path analysis
CPC: → Cost-per-click
CPM: → Critical path method
CQS: → Command-Query Separation
CR: → Candidate Recommendation
Craft: A pastime or a profession that requires particular skills and knowledge of skilled work. †\n
CRAP: → Create, Replicate, Append, Process
Crawler: An Internet bot that systematically browses the World Wide Web, typically for the purpose of Web indexing (web spidering). Web search engines and some other sites use Web crawling or spidering software to update their web content or indices of others sites’ web content. †\n
Crawling: The systematic browsing of the World Wide Web for the purpose of indexing. †\n
Create, Read, Update, Delete: The four basic functions of persistent storage. †\n
Create, Replicate, Append, Process: A variation of CRUD. †\n
Critical CSS: The minimum of CSS needed to show a styled web page. Focus is usually on the immediately visible part of a page sitting at the top or “above the fold.” The respective CSS rules are then inlined, that is, embedded in a style element within the page’s head element.
Critical path: The longest stretch of dependent project activities and the time required to complete them from start to finish. †\n
Critical path analysis: → Critical path
Critical path method: → Critical path
Critical rendering path: A model for the steps needed to render a web page, and optimize its rendering. The critical rendering path includes the building of DOM (Document Object Model) and CSSOM (CSS Object Model), changes to both through the execution of JavaScript, the construction of the render tree, layout, and paint.
CRM: → Customer Relationship Management
cron: A time-based job scheduler on Unix-like computer operating systems. Users that set up and maintain software environments use cron to schedule jobs (commands or shell scripts) to run periodically at fixed times, dates, or intervals. cron is most suitable for scheduling repetitive tasks. Scheduling one-time tasks can be accomplished using the associated at utility. cron was first released in 1975. †\n
Cron job: A job (command) to be executed by cron.
Crontab: A configuration file that specifies shell commands to run periodically on a given schedule. The crontab files are stored where the lists of jobs and other instructions to the cron daemon are kept. Users can have their own individual crontab files and often there is a system-wide crontab file (usually in /etc or a subdirectory of /etc) that only system administrators can edit. †\n
Cross-Origin Read Blocking: A security feature that helps mitigate side-channel attacks. CORB prevents the browser from delivering certain cross-origin responses to a web page, for example, when these responses would contain sensitive information.
Cross-Origin Resource Sharing: A mechanism that allows restricted resources on a web page to be requested from another domain outside the domain from which the first resource was served. A web page may freely embed cross-origin images, style sheets, scripts, iframes, and videos. Certain “cross-domain” requests are forbidden by default by the same-origin security policy. CORS defines a way in which a browser and server can interact to determine whether it is safe to allow the cross-origin request. †\n
Cross-Origin Resource Policy: A policy set by the Cross-Origin-Resource-Policy HTTP header that lets websites and applications opt into protection against certain requests from other origins (such as those issued with elements like <script> and <img>), to mitigate speculative side-channel as well as cross-site script inclusion attacks. CORP is an additional layer of protection beyond the default same-origin policy. ‡\n
Cross-Origin-Embedder-Policy: An HTTP response header preventing a document from loading cross-origin resources that do not explicitly grant the document permission (using CORP or CORS). ‡\n
Cross-Site Request Forgery: A type of malicious exploit of a website where unauthorized commands are transmitted from a user that the web application trusts. There are many ways in which a malicious website can transmit such commands; specially-crafted image elements, hidden forms, and JavaScript XMLHttpRequests, for example, can all work without the user’s interaction or even knowledge. Unlike cross-site scripting (XSS), which exploits the trust a user has for a particular site, CSRF exploits the trust that a site has in a user’s browser. †\n
Cross-Site Script Inclusion: A vulnerability which uses the circumstance that a script referenced through a script element is exempt from the same-origin policy, as scripts need to work across domains. An attacker may access and use what is being loaded using the respective script, and thus leaked across origins.
Cross-Site Scripting: A type of computer security vulnerability typically found in web applications. XSS enables attackers to inject client-side scripts into web pages viewed by other users. A cross-site scripting vulnerability may be used by attackers to bypass access controls such as the same-origin policy. †\n
Cross-Site WebSocket Hijacking: An attack similar to Cross-Site Request Forgery (CSRF), on a WebSocket handshake, which may allow read/write communication on the respective WebSocket connection. ℹ︎ is.gd/cGQ4bj\n
CRP: → Critical rendering path
CRUD: → Create, Read, Update, Delete
CSCS: → Customized Scripting in C#
CSP: → Content Security Policy
CSR: → Client-Side Rendering
CSRF: → Cross-Site Request Forgery
CSS: → Cascading Style Sheets
CSS framework: → HTML/CSS framework
CSS lock: CSS code that results in a lower and an upper bound for a particular styling, like a minimum and maximum font size that is otherwise fluid. CSS locks can rely on a single declaration but may include both more declarations as well as media queries. The term “CSS lock” may have first been coined in 2016 by Tim Brown. ℹ︎ is.gd/FjK3B8\n
CSS Modules: As a CSS Module, a CSS file in which all class and animation names are by default scoped locally. ℹ︎ github.com/css-modules/css-modules\n
CSS Object Model: A map of all CSS selectors and relevant properties for each selector in the form of tree, with root node, sibling, descendant, child, and other relationships. The CSSOM is similar to the Document Object Model (DOM). Both of them are part of the critical rendering path which is a series of steps that must happen to properly render a website. ‡\n
CSS preprocessor: A program that allows to generate CSS from the preprocessor’s own unique syntax. There are many CSS preprocessors to choose from, however most CSS preprocessors add features that do not exist in pure CSS, such as mixins, selector nesting, or inheritance selectors. These features make the CSS structure more readable and easier to maintain. ‡\n
CSS Zen Garden: A web development resource “built to demonstrate what can be accomplished visually through CSS-based design.” Style sheets contributed by web designers and developers from around the world are used to change the visual presentation of a single HTML file, producing hundreds of different designs. Aside from reference to an external CSS file, the HTML markup itself never changes. All visual differences are the result of the CSS (and supporting imagery). CSS Zen Garden is a poster child for CSS-only redesigning. It was created in 2003 by Dave Shea. † ℹ︎ csszengarden.com\n
CSS-in-JS: A styling technique in which JavaScript is used to style components. When this JavaScript is parsed, CSS is generated (usually as a style element) and attached to the DOM. CSS-in-JS allows to abstract CSS to the component level itself, using JavaScript to describe styles in a declarative and maintainable way. There are multiple implementations of this concept such as styled components or JSS. † ℹ︎ cssinjs.org\n
CSS-Tricks: A popular web development online magazine and CSS resource. CSS-Tricks was founded in 2007 by Chris Coyier. ℹ︎ css-tricks.com\n
CSSOM: → CSS Object Model
CSV: → Comma-Separated Values
CSWSH: → Cross-Site WebSocket Hijacking
CTA: → Call to Action
CTR: → Click-through rate
Cumulative Layout Shift: A metric, the so-called layout shift score, for measuring visual stability. The layout shift score is based on a multiplication of impact fraction and distance fraction. ℹ︎ web.dev/cls\n
curl: A computer software project providing a library (libcurl) and command-line tool (curl) for transferring data using various network protocols. The name stands for “Client URL,” which was first released in 1997. † ℹ︎ curl.se\n
Currying: The technique of converting a function that takes multiple arguments into a sequence of functions that each take a single argument. †\n
Custom data attribute: An attribute in no namespace whose name starts with the string data-, has at least one character after the hyphen, is XML-compatible, and contains no ASCII upper alphas. Custom data attributes are intended to store custom data, state, annotations, and similar, private to the page or application, for which there are no more appropriate attributes or elements. §
Custom element: → Autonomous custom element; → Customized built-in element
Custom property: A CSS property that is prefixed with --, like --example-name, and whose value can be used in other declarations using the var() function. Custom properties are scoped to the element(s) they are declared on, and participate in the cascade: The value of a custom property is that from the declaration decided by the cascading algorithm. Custom properties are also known as CSS variables. ‡ ℹ︎ w3.org/TR/css-variables-1\n
Customer Effort Score: A customer service metric that measures the experience with a product or service. Customers document their experience on a 7-point Likert scale ranging from “Very Difficult” to “Very Easy.” The result can be used to assess how much effort is needed to use the respective product or service, and to predict further use.
Customer Relationship Management: An approach to manage a company’s interaction with current and potential customers. It uses data analysis about customers’ history with a company to improve business relationships with customers, specifically focusing on customer retention and ultimately driving sales growth. †\n
Customized built-in element: A type of custom element for a web component. Customized built-in elements inherit from basic HTML elements. To create a customized built-in element one has to specify which element it extends, and to use it one writes out the basic element but specifies the name of the custom element through an is property. ‡\n
Customized Scripting in C#: A basic scripting language based on C#. CSCS features no functions, methods, and Boolean values. It was presented in 2016 by Vassili Kaplan. ℹ︎ github.com/vassilych/cscs\n
Cutting the mustard: The succeeding under difficult circumstances, an expression attributed to BBC developers in the context of user agent detection.
CVE: → Common Vulnerabilities and Exposures
CVS: → Concurrent Versions System
CVSS: → Common Vulnerability Scoring System
Cyan, Magenta, Yellow, and Key: As the CMYK color model, a subtractive color model used in color printing, and also used to describe the printing process itself. CMYK refers to the four ink plates used in some color printing: cyan, magenta, yellow, and key (black). The CMYK model works by partially or entirely masking colors on a lighter, usually white, background. The ink reduces the light that would otherwise be reflected. Such a model is called subtractive because inks “subtract” the colors red, green, and blue from white light. White light minus red leaves cyan, white light minus green leaves magenta, and white light minus blue leaves yellow. †\n
Cycle time: The amount of time between the start of work on a task to the time it is delivered.
Cyclomatic complexity: A software metric used to indicate the complexity of a program. It is a quantitative measure of the number of linearly independent paths through a program’s source code, and is computed using the control-flow graph of the program. The nodes of the graph correspond to indivisible groups of commands of a program, and a directed edge connects two nodes if the second command might be executed immediately after the first command. Cyclomatic complexity may also be applied to individual functions, modules, methods, or classes. It was developed in 1976 by Thomas J. McCabe, Sr. †\n

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\nAppendix

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\nWikipedia Contributions

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This book uses material from the following Wikipedia articles:

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.htaccess
.htpasswd
.NET Framework
8.3 filename
A/B testing
Abstract data type
Accelerated Mobile Pages
Acceptance test-driven development
Acceptance testing
Access control
Access key
Access token
Access-control list
Accessibility
ACID
Acknowledgement (data networks)
Acqui-hiring
ActionScript
Active redundancy
Active Server Pages
Active users
Address Resolution Protocol
Adobe ColdFusion
Adobe Dreamweaver
Adobe Flash
Adobe Flash Player
Adobe Photoshop
ads.txt
Advanced Encryption Standard
Advanced persistent threat
Affordance
Agile software development
AirMosaic
Ajax (programming)
ALGOL
Algorithm
Aliasing
Amazon Route 53
Amazon S3
Amazon Simple Queue Service
Amazon Virtual Private Cloud
Amazon Web Services
Angular (web framework)
AngularJS
Animation
Anonymous function
Anti-pattern
Apache Maven
Apache Subversion
Apache Tomcat
Applet
Application programming interface
Application software
APT (software)
Arena (web browser)
Array data structure
ASP.NET
Aspect ratio (image)
AssemblyScript
Assignment (computer science)
Assistive technology
Assistive Technology Service Provider Interface
Association for Computing Machinery
Asynchronous module definition
Asynchrony (computer programming)
at (command)
Attribute (computing)
Augmented reality
Authentication
Authorization
Automation
AV1
Babel (transpiler)
Backlink
Backup
Backward compatibility
Bada
Bandwidth (computing)
Base64
Baseline (typography)
Bash (Unix shell)
Basic access authentication
BBCode
Behavior-driven development
Best practice
Bézier curve
Bidirectional text
Big O notation
Binary large object
Binary number
Binary search algorithm
Bitbucket
Black hat (computer security)
Black-box testing
Blacklist (computing)
Blink (browser engine)
Blog
Blogosphere
BMP file format
Bookmark (digital)
Bookmarklet
Boolean data type
Border Gateway Protocol
Bounce rate
Boundary value problem
Bourne shell
Branching (version control)
Braille
Breadcrumb navigation
Breakpoint
Brotli
Browser engine
Browser extension
Browser Helper Object
Browser sniffing
Browsing
Bug tracking system
Bugzilla
Bushnell’s Law
Byte order mark
Bytecode
Cache (computing)
California Consumer Privacy Act
Call to action (marketing)
Callback (computer programming)
Camel case
Camino (web browser)
Canonical link element
CAP theorem
CAPTCHA
Caret
Cascading Style Sheets
CDATA
Certificate authority
Chaos engineering
CheiRank
Chrome OS
Chromium (web browser)
Cipher
Class (computer programming)
Class variable
Classless Inter-Domain Routing
Clean URL
Click-through rate
Clickjacking
Client (computing)
Client-side
Cloaking
Clojure
Closure (computer programming)
Cloud computing
Cloud storage
CMYK color model
CNAME record
Coalescing (computer science)
Code coverage
Code golf
Code point
Code of conduct
Code refactoring
Code review
Code smell
CodePen
CoffeeScript
ColdFusion Markup Language
Color blindness
Color management
Color scheme
Color wheel
Comma-separated values
Command (computing)
Command-line interface
Command-query separation
Comment (computer programming)
Common Gateway Interface
Common Vulnerabilities and Exposures
Common Vulnerability Scoring System
CommonJS
Communication protocol
Community of practice
Compatibility mode
Compiler
Complementary colors
Component-based software engineering
Composite Capability/Preference Profiles
Computer cluster
Computer code
Computer compatibility
Computer file
Computer network
Computer programming
Concurrency (computer science)
Concurrent Versions System
Conditional (computer programming)
Conditional comment
Cone of Uncertainty
Conflict of interest
Consistency
Console application
Constant (computer programming)
Constructor (object-oriented programming)
Content (media)
Content delivery network
Content management system
Content negotiation
Content Security Policy
Content sniffing
Context switch
Continuous delivery
Continuous deployment
Continuous integration
Control flow
Convention over configuration
Conway’s law
Corporate design
Corporate identity
Country code top-level domain
Coupling (computer programming)
Craft
Create, read, update and delete
Critical path method
cron
Cross-origin resource sharing
Cross-site request forgery
Cross-site scripting
Cryptographic nonce
Cryptography
CSS box model
CSS framework
CSS image replacement
CSS Zen Garden
CSS-in-JS
cURL
Currying
Customer relationship management
Cyclomatic complexity
D3.js
Daemon (computing)
Dark pattern
Darknet
Dart (programming language)
Data
Data center
Data compression
Data control language
Data definition language
Data lake
Data manipulation language
Data storage
Data stream management system
Data type
Data validation
Data visualization
Data warehouse
Database
Database engine
Database index
Database normalization
Database server
Dead code elimination
Debugging
Deep web
Denial-of-service attack
Deno (software)
Dependency injection
Dependency inversion principle
Deployment environment
Deprecation
Descender
Design
Design by contract
Design pattern
Device fingerprint
DevOps
Dialog box
Digital display advertising
Digital rights management
Disabilities affecting intellectual abilities
Disability Discrimination Act 1995
Disciplined agile delivery
Display contrast
Display resolution
Distributed Concurrent Versions System
Distributed object communication
Distributed version control
Dither
Django
DMARC
DMZ (computing)
DNS over HTTPS
DNS root zone
DNS spoofing
DocBook
Docker (software)
Document Object Model
Document Style Semantics and Specification Language
Document type declaration
Document type definition
Documentation
Dojo Toolkit
Domain name
Domain name registrar
Domain Name System
Domain Name System Security Extensions
Domain-driven design
DomainKeys Identified Mail
Don’t repeat yourself
Doorway page
Dots per inch
Downtime
Duck typing
Duplicate code
Dynamic Host Configuration Protocol
Dynamic HTML
Dynamic Language Runtime
Dynamic web page
Dyslexia
E-commerce
EBCDIC
Eclipse (software)
Ecma International
ECMAScript
Effectiveness
Efficiency
Electron (software framework)
Electronic Frontier Foundation
Em (typography)
Emacs
Email
Email spoofing
Email address
Empty string
Encapsulation (computer programming)
End-of-file
Environment variable
Equality Act 2010
Error
Ethics
Etiquette
European Accessibility Act
Event (computing)
Event loop
Event-driven architecture
Eventual consistency
Exception handling
Exception handling syntax
Exit status
Express.js
Extensible Application Markup Language
Extract, transform, load
Extreme programming
Eye tracking
Facade pattern
Facebook Instant Articles
Facebook Platform
Fagan inspection
Failover
Fallback
False positives and false negatives
Favicon
Feature creep
Feature detection (web development)
Feature phone
Federal Information Processing Standards
Federated Learning of Cohorts
Federation (information technology)
FIFO (computing and electronics)
Figma (software)
File locking
File manager
File system
File Transfer Protocol
Filler text
Fingerprint (computing)
Fitts’s law
Flash of unstyled content
Flat design
Flock (web browser)
Fluent Design System
FOAF (ontology)
Folksonomy
Font
Foobar
Foreign key
Fork (software development)
Form (HTML)
Formatting Output Specification Instance
Forward compatibility
Forward secrecy
Fragment identifier
Frame (World Wide Web)
Frame rate
Framekiller
Free and open-source software
Free Software Foundation
Free variables and bound variables
Front and back ends
FTPS
Fully qualified domain name
Function as a service
Functional programming
Functional testing
Fuzzing
Gamma correction
Garbage collection (computer science)
Garbage in, garbage out
Gateway (telecommunications)
Gecko (software)
General Data Protection Regulation
Generic top-level domain
Geo-fence
GIF
Git
GitHub
GitHub Copilot
GitLab
GNU
GNU General Public License
GNU Project
Go (programming language)
Goanna (software)
Golden ratio
Google Cloud Platform
Google Lighthouse
Google PageSpeed Tools
Google TalkBack
Google Web Server
Gopher (protocol)
Grapheme
Graphical user interface
Graphics processing unit
GraphQL
GRASP (object-oriented design)
Greasemonkey
Greenfield project
Grid (graphic design)
Grid computing
Guetzli
gulp.js
Gutter
gzip
Hackathon
Hacker
Haml
Hardware security module
Hash function
Hash table
Hashtag
Head-of-line blocking
Headless software
Helper class
Hexadecimal
High Efficiency Image File Format
Higher-order function
Hick’s law
Hidden file and hidden directory
Hit (Internet)
HITS algorithm
HMAC
HMAC-based One-Time Password
Home page
Home screen
Hooking
Host (network)
Host Identity Protocol
Hostname
HSL and HSV
HTML
HTML element
HTML5 Boilerplate
HTTP cookie
HTTP Flood
HTTP Strict Transport Security
HTTP/2
HTTP/3
HTTPS
HTTPS Everywhere
Human-computer interaction
Hungarian notation
Hype cycle
Hypertext
Hypertext Transfer Protocol
Hypervisor
IBM Home Page Reader
IBM WebExplorer
ICANN
Icon (computing)
Identifier
IDL (programming language)
Image
Image map
Immutable object
Indexed color
Indexed Database API
Industrial design
Information architecture
Information design
Information foraging
Information overload
Information retrieval
Information security
Information security operations center
Infrastructure as a service
Infrastructure as code
Inheritance (object-oriented programming)
Initiative for Open Authentication
Inline linking
Input/output
Instance variable
Institute of Electrical and Electronics Engineers
Integer
Integer (computer science)
Integrated development environment
Intellectual property
IntelliJ IDEA
Interaction design
Interactive Advertising Bureau
Interface (computing)
Interface description language
Interface segregation principle
International Organization for Standardization
International Telecommunication Union
Internationalization and localization
Internationalized Resource Identifier
Internet
Internet Architecture Board
Internet Assigned Numbers Authority
Internet Engineering Task Force
Internet Explorer
Internet Information Services
Internet Message Access Protocol
Internet Protocol
Internet Relay Chat
Internet service provider
Internet Society
InterNIC
Interoperability
InterPlanetary File System
Interpolation
Interstitial webpage
Intranet
Inversion of control
IOPS
iOS
IP address
iptables
IPv4
IPv6
JAR (file format)
Jasmine (JavaScript testing framework)
Java (programming language)
Java Database Connectivity
Java Development Kit
Java servlet
Java virtual machine
JavaFX
JavaScript framework
JavaScript library
JavaScript Style Sheets
JavaServer Pages
JAWS (screen reader)
Jenkins (software)
Jetty (web server)
Jinja (template engine)
Jira (software)
Joint Photographic Experts Group
Joomla
JPEG
jQuery
JScript
JSLint
JSON
JSON Feed
JSON Web Encryption
JSON Web Signature
JSON Web Token
JSON-LD
JSONP
Just-in-time compilation
Just-in-time manufacturing
K-Meleon
Kanban (development)
Kerberos (protocol)
Kerning
Key (cryptography)
Key frame
Key-value database
Knowledge Graph
Kubernetes
LAMP (software bundle)
Landing page
Laravel
Latency (engineering)
LaTeX
Law of conservation of complexity
Lazy loading
Lead programmer
Lead time
Leading
Lean thinking
Legibility
Less (stylesheet language)
Let’s Encrypt
Letter case
Letter-spacing
libwww
Light-on-dark color scheme
Lightweight Directory Access Protocol
Lightweight markup language
Likert scale
Link farm
Link rot
Linked data
lint (software)
Linux
Linux Standard Base
Liskov substitution principle
Lisp (programming language)
List of DNS record types
List of HTTP status codes
List of XML and HTML character entity references
Literal (computer programming)
Little’s law
Load balancing (computing)
Local area network
Local variable
Locale (computer software)
Location information server
Log file
Login
Long-term support
Look and feel
Lossless compression
Lossy compression
Lynx (web browser)
MAC address
Machine learning
macOS
Macromedia HomeSite
MacWWW
Magic (programming)
Maintainability
Maintenance (technical)
Makefile
MAMP
Man-in-the-middle attack
Markdown
Marketing
Markup language
Massively parallel
Masthead (American publishing)
Material Design
Mathematical markup language
Mathematical optimization
MathML
MD2 (hash function)
MD4
MD5
MD6
MEAN (software bundle)
Media (communication)
Media queries
Media type
Memoization
Menu (computing)
Merge (version control)
Message authentication code
Meta element
Metadata
Method (computer programming)
Method stub
Metro (design language)
Microformat
Microservices
Microsite
Microsoft Active Accessibility
Microsoft Edge
Microsoft FrontPage
Microsoft Silverlight
Microsoft Windows
Middleware
MIME
Minification (programming)
Minimum viable product
Mixin
Mobile computing
Mobilegeddon
Modal window
Model-view-controller
Model-view-viewmodel
Modernizr
Modular design
Monolithic application
Monorepo
Mosaic (web browser)
Moving Picture Experts Group
Multi-factor authentication
Multimedia
Multiple inheritance
Muphry’s law
Murphy’s law
Mustache (template system)
Mutual authentication
MySQL
Name binding
Name server
Namespace
NaN
National Institute of Standards and Technology
Native (computing)
NativeScript
Natural key
Natural user interface
Negative space
Nesting (computing)
Net Promoter
Netscape Navigator
Network address translation
Network domain
Network packet
Newbie
Newline
News aggregator
Next.js
Nginx
Ninety-ninety rule
Nmap
Node (computer science)
Node.js
nofollow
Non-disclosure agreement
NonVisual Desktop Access
Normative
NoSQL
npm (software)
Null coalescing operator
Null device
Null pointer
Number sign
Numerical digit
Nuxt.js
OAuth
Obfuscation (software)
Object (computer science)
Object-oriented programming
Observer pattern
OCSP stapling
OKR
One-time password
Online analytical processing
Online Certificate Status Protocol
Online transaction processing
OOCSS
Open source
Open-closed principle
OpenID
OpenType
Opera Mini
Operand
Operating system
Operator (computer programming)
Operator (mathematics)
Orca (assistive technology)
Orthogonality (programming)
Orthographic ligature
OS-level virtualization
OSI model
Out of memory
Over-the-air programming
OWASP
Page layout
PageRank
Pageview
Pair programming
Paper prototyping
Paradigm
Parallax scrolling
Parameter (computer programming)
Pareto principle
Parkinson’s law
Parsing
Patch (computing)
Path (computing)
PATH (variable)
Pay-per-click
Payload (computing)
Paywall
PCDATA
PDF
Penetration test
Perceived performance
Percent-encoding
Performance indicator
Perl
Permalink
Persona (user experience)
Personal data
PhantomJS
Phishing
PHP
PhpStorm
ping (networking utility)
pip (package manager)
Pixel
Plain text
Plane (Unicode)
Platform as a service
Plug-in (computing)
Pointer (computer programming)
Pointing device
Polyfill (programming)
Polymer (library)
Pop-up ad
Port (computer networking)
Portable Network Graphics
Post Office Protocol
PostCSS
Posting style
Postmortem documentation
PowerShell
Predication (computer architecture)
Prefetching
Presto (browser engine)
Primary key
Primitive data type
Privacy
Program optimization
Programming language
Progressive enhancement
Progressive web application
Property (programming)
Proxy server
Public key certificate
Punycode
Puppet (software)
Push technology
Python (programming language)
qooxdoo
Quality (business)
Quality assurance
Quality control
Queries per second
Query
Query language
QUIC
Quirks mode
Race condition
RADIUS
Raku (programming language)
Random variable
Random-access memory
Ranking
Raster graphics
Rate limiting
React (web framework)
React Native
Reactive programming
Read-eval-print loop
Readability
README
Real user monitoring
RealAudio
RealVideo
Recursion (computer science)
Redundancy (engineering)
Redux (JavaScript library)
Reed-Solomon error correction
Referential transparency
Regular expression
Relational data stream management system
Relational database
Relational model
Remote Desktop Protocol
Remote procedure call
Replay attack
Request for Comments
Reserved word
Resource Description Framework
Responsibility assignment matrix
Responsive web design
Reverse proxy
Revision tag
RGB color model
Rich Text Format
Rich web application
Right-to-left
Robots exclusion standard
Robustness principle
Root directory
Root element
Root name server
Rooting (Android)
Round-trip delay time
Router (computing)
Routing
Routing table
RPM Package Manager
RSS
RTFM
Rubber duck debugging
Ruby (programming language)
Ruby on Rails
Runbook
Safari (web browser)
Same-origin policy
Sandbox (computer security)
Sandbox (software development)
Sass (stylesheet language)
Scaled agile framework
Scope (computer science)
Screen magnifier
Screen reader
Scripting language
Scrolling
Scrum (software development)
SeaMonkey
Search engine indexing
Search engine marketing
Secure Shell
Security Assertion Markup Language
Security hacker
Security operations center
security.txt
Search engine optimization
Selenium (software)
Semantic Web
Semantics (computer science)
Sender Policy Framework
Separation of concerns
Serialization
Serif
Server (computing)
Server farm
Server Name Indication
Server-side
Serverless computing
Service discovery
Service-oriented architecture
Service-level agreement
Session (computer science)
Session hijacking
Set (abstract data type)
SGML entity
Shebang (Unix)
Shell (computing)
Shim (computing)
Simple Mail Transfer Protocol
Single point of failure
Single responsibility principle
Single-page application
Site map
Sitemaps
Slowloris (computer security)
Smoke testing (software)
Snake case
SOA record
SOAP
Soft launch
Software
Software as a service
Software bug
Software crisis
Software deployment
Software development
Software development kit
Software framework
Software modernization
Software prototyping
Software testing
Software versioning
SOLID
Solution stack
Source lines of code
Source-code editor
Source-to-source compiler
Spaghetti code
Spam
Spamdexing
Spamming
SPDY
Specification (technical standard)
Spectre (security vulnerability)
Speech synthesis
Spike (software development)
Spinner (computing)
Splash screen
Spoofing attack
SQL
SQL injection
Squarespace
sRGB
SSH File Transfer Protocol
Stack (abstract data type)
Stack Overflow
Stand-up meeting
Standard Generalized Markup Language
State (computer science)
Statement (computer science)
Static web page
Storage area network
Strategic design
Stream (computing)
Streaming media
String (computer science)
Structural similarity
Style sheet (web development)
Stylus (stylesheet language)
Subject Alternative Name
Subject-matter expert
Subnetwork
Subresource Integrity
Subroutine
Superkey
Superuser
Surface web
Surrogate key
Switch statement
Symbol (programming)
Symfony
Synchronized Multimedia Integration Language
Syntactic sugar
Syntax (programming languages)
syslog
Tabnabbing
Tag management system
Tag soup
tar (computing)
Tcl
Technical debt
Technical standard
Technology roadmap
Telnet
Template processor
Ternary operation
Test-driven development
TeX
Textile (markup language)
The Open Group Architecture Framework
Theme (computing)
Third-party source
Thread (computing)
Three-click rule
Time to first byte
Time to live
Time-based One-Time Password
Timed text
Timestamp
Tizen
Tokenization (data security)
TOML
Top-level domain
TOP500
Tor (anonymity network)
Tracing (software)
Transclusion
Transcreation
Transmission Control Protocol
Transport Layer Security
Travis CI
Tree (data structure)
Tree shaking
Trident (software)
TrueType
Trust on first use
TrustRank
Turing completeness
Type conversion
Type design
Type system
Typeface
TypeScript
TYPO3
Typography
UDP flood attack
Unicode
Unicode Consortium
Unicode equivalence
Unified Modeling Language
Uniform Resource Characteristic
Uniform Resource Identifier
Uniform Resource Name
Uninitialized variable
Unique selling proposition
Unit testing
Universal Access
Universal design
Universally unique identifier
Uniwidth typeface
Unix
Unix philosophy
URL
URL redirection
Usability
Usability inspection
Usability testing
Use case
Usenet
User (computing)
User agent
User Datagram Protocol
User experience
User interface
User interface markup language
User story
User-centered design
Userscript
UTF-8
UTF-16
UTF-32
UTM parameters
Validator
Value (computer science)
Value-driven design
Variable (computer science)
Variable fonts
Vector graphics
Velocity (software development)
Verification and validation
Version control
vi
Viewport
Vim (text editor)
Virtual inheritance
Virtual LAN
Virtual machine
Virtual private cloud
Virtual private network
Virtual reality
Virtualization
Visual Basic for Applications
Visual impairment
Visual Studio Code
Voice over IP
Voice phishing
VoiceOver
VoiceXML
Vue.js
W3C Geolocation API
WAR (file format)
Waterfall model
Web 2.0
Web Accessibility Initiative
Web analytics
Web application
Web application firewall
Web beacon
Web browser
Web colors
Web Components
Web content
Web Content Accessibility Guidelines
Web crawler
Web design
Web development
Web development tools
Web feed
Web framework
Web IDL
Web indexing
Web navigation
Web Open Font Format
Web page
Web performance
Web platform
Web portal
Web resource
Web service
Web standards
Web Standards Project
Web storage
Web syndication
Web template system
Web tracking
Web typography
Web worker
WebAssembly
WebAuthn
WebDAV
WebGL
WebKit
WebM
Webmaster
Webmention
WebP
Webpack
Website
Website wireframe
WebSocket
WebVTT
Well-formed document
Wget
WHATWG
White-box testing
Whitelisting
Whitespace character
WHOIS
Wide area network
Widows and orphans
Wiki
Window-Eyes
Windows Aero
Wireless Application Protocol
Wireless Markup Language
Wix.com
WordPress
Workaround
World Wide Web
World Wide Web Consortium
WorldWideWeb
Wrapper function
Write once, run anywhere
WYSIWYG
X.509
x-height
XForms
XHP
XHTML
XLink
XML
XML Schema (W3C)
XML-RPC
XMLHttpRequest
XPath
XPointer
XQuery
XSL
XUL
Yahoo! Query Language
YAML
Yandex Browser
Year 2000 problem
You aren’t gonna need it
YUI Library
Z shell
Zero-based numbering
Zero-configuration networking
Zip (file format)
Zombie cookie
Zone file

\n\n

The original works, which have been released under a CC BY–SA 3.0 license, have been shortened and edited.

\n\n

\nMDN Web Docs Contributions

\n\n

This book uses material from the following articles by Mozilla contributors:

\n\n

The original works, which have been licensed under CC BY–SA 2.5, have been edited.

\n\n\n

\nFeedback

\n\n\n

This content is not available in the sample book. The book can be purchased on Leanpub at https://leanpub.com/web-development-glossary.

\n\n\n

\nAbout The Web Development Glossary\n

\n\n

Written and compiled by Jens Oliver Meiert.

\n\n

Published by Frontend Dogma, c/o Jens Oliver Meiert, Apartado de correos 3, 36070 Pontevedra, Spain.

\n\n

Editor: Gabriele Kretzschmar
Consultants: Ganesh Subramanian, Yaroslav Kiyenko

\n\n

The Web Development Glossary is licensed under a CC BY–SA 4.0 (Attribution–ShareAlike 4.0 International) license.

\n\n\n\n

While this book has been produced with great care, the author, publisher, and contributors assume no liability for the up-to-dateness, correctness, and completeness of the information provided. Liability claims based on the use or non-use of this information are excluded, unless author, publisher, or contributors can be proven to have acted with intent or gross negligence. Use of the information in this book is on your own responsibility. When using code or content subject to open-source licenses or the rights of others, it is on you to ensure compliance with the respective licenses and rights.

\n\n

Contact +34-610859489 or info@frontenddogma.com for questions and more information.

\n\n

Follow Frontend Dogma on Mastodon (and other networks).

\n\n

[1.5.8]

\n\n

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\nThe Web Development Glossary

Table of Contents

\nIntroduction

\nAcknowledgments

\nThe Web Development Glossary

\n!./_

\n0–9

\nA

\nB

\nC

\nD

\nE

\nF

\nG

\nH

\nI

\nJ

\nK

\nL

\nM

\nN

\nO

\nP

\nQ

\nR

\nS

\nT

\nU

\nV

\nW

\nX

\nY

\nZ

\nAppendix

\nWikipedia Contributions

\nMDN Web Docs Contributions

\nFeedback

\nAbout The Web Development Glossary\n