"CVS is the Concurrent Versioning System--the most popular free source code manager around. Pretty much every open source or free software developer has at some time or other crossed swords with it. In addition, many companies use CVS as a cheaper alternative to more costly SCMs such as Perforce or ClearCase to manage their internal source code.
"A source code manager allows you to 'remember' old known-good states of your source code, track the changes to your code over time, and allow development by several developers on the same source code at the same time. CVS provides basic versioning functionality, including branching (allowing several versions of the source code to be developer concurrently) and tagging (remembering snapshots of the repository). It has a well-earned reputation as a solid and reliable piece of software.
"One of the key issues when dealing with source code management is deciding who can get at it. In the open source and free software world, we generally want as many people as possible to have access to our software, but we don't want just anyone changing our copy of it. Nor do we want to allow just anyone access to our machine to do with it as they will..."
