Git is a free and widely-used version control system. It allows researchers to preserve, track, and revert to different versions of their project files in what are called Git Repositories. Software Carpentry offers useful tutorials for version control with Git. Github is a well-designed and popular host for Git repositories, and also offers a graphical application for managing repositories. It is used for sharing project files and collaborating. Github Guides are excellent tutorials for learning how to use Github.