Git is an awesome free and open source, distributed version control system designed to handle everything from small to very large projects with speed and efficiency, no matter in which language are you working. Very useful for multiple developers working at the same project.
Initially designed and developed by Linus Torvalds for Linux kernel development.
There are a few free servers for source code with Git, one of the most popular is Github.
Here is a quick reference guide for the most common Git commands.
You can download it from here: Git Quick Reference.
Enjoy it and feedback is welcome !!