For the past few years, since the introduction of multicore CPUs into the mainstream, people have been talking about concurrency and several languages have adopted concurrency through libraies or even changed part of the language itself or, even more drastically, new languages have showed up trying to focus from the start on concurrency. Concurrency is in fact very important but very badly understood. This book plans to serve as an introduction to the several ways concurrency is leveraged in different programming languages by exposing in a clear language (without too much mathematics!) the different concepts of different concurrency models and their practical use. This book aims to guide you at the beginning and intermediate stages of discovering concurrency and provides insights on where to find further information in case you want to dwell more into concurrency, either the theoretical or the practical side.