CVS (Concurrent Versions System) is aversion control system.
CVS can help people who work on the same project at the same time, and it can save every version of your software you have ever created without wasting an enormous amount of disk space. It stores all the versions of a file in a single file in a clever way that only stores the differences between versions.
The website for CVS is http://www.nongnu.org/cvs/ . You can download the software and find manual there.
