CVS is a version control system, which allows multiple developers to access the current code and to submit changes. Although CVS is being gradually replaced by more modern software, such as Subversion and git, it's still widely used by free software projects. Old versions of MadWifi used CVS before being converted to Subversion.

The homepage of CVS is http://www.nongnu.org/cvs/

CVS is present in virtually all Linux distributions.