Git is a distributed source control system.
Git is a source control system that allows for many people to work on the same project simultaneously. It is distributed, makes it possible for many different branches of the same project to co-exist at the same time, and offers many other advanced features.
Git was originally authored by Linus Torvalds, the creator of the Linux kernel, and the official Git homepage is at git-scm.com
For more information, see wikipedia