CVS is very popular tool in HEP and is used to manage very large projects. However, with its ability to track changes and recover old versions it is also invaluable for individuals working on their own with any type of source that they need to develop and maintain. It is particularly powerful, when coupled with SSH for laptop users. They can set up the "Repository" (the place where CVS holds the master copy of all its files) on their main computing server and then, while on-line use CVS to get a copy onto their laptop. After that they can work off-line, and at some convenient point, go back on-line to update the Repository. That way the source backup is dealt with on the server. Also it is possible to switch between on-line development on the server and off-line development on the laptop with ease.
In the meantime look at the cvs: A Tool for Code Management section of the Introductory Computing Manual and the CVS Documentation