Concurrent Versions System (CVS)
CVS is a system that lets groups of people work simultaneously on groups of files. A version control system keeps a history of the changes made to a set of files. For a developer, that means being able to keep track of all the changes you've made to a program during the entire time you've been developing it.
CVS clients communicate with CVS servers over a local area network or the internet (in general: a TCP/IP based network). When you use a CVS client, it sends your data and CVS commands to the server and receives new data and results from the server and stores or displays them on your client machine.
CVS manuals, tutorials, server setup instructions, etc.