Intro to Git
From Wikipedia:
Git is a version control system for tracking changes in computer files and coordinating work on those files among multiple people. It is primarily used for source code management in software development, but it can be used to keep track of changes in any set of files.
As with most other distributed version control systems, and unlike most client–server systems, every Git directory on every computer is a full-fledged repository with complete history and full version tracking abilities, independent of network access or a central server.
Git is widely used by just about every group of professionals that regularly code, particularly those that work collaboratively on programming projects. It is a very good tool to learn and there are many, many resources available to you: