Git is the most popular revision control system. For that reason, all the code used in this book is stored in Bitbucket (https://bitbucket.org/). If you don't have it already, install Git. Distributions for all the popular operating systems can be found at http://git-scm.com.
Many graphical interfaces are available for Git; some of them being Tortoise (https://code.google.com/p/tortoisegit), Source Tree (https://www.sourcetreeapp.com), and Tower (http://www.git-tower.com/).