CVS: Concurrent Version System
CVS provides a network-transparent way for developers to share source control management. It is the most widely used open-source version control software. For more information on CVS, please see the CVS Web site.
WebCvs for browsing source code and easy downloads
If you want to browse the code and only make occasional downloads, you may want to use WebCVS. It provides a convenient, Web-based interface for browsing and downloading the latest version of the source code and documentation. You can also view each file's revision history, display the differences between individual revisions, determine which revisions were part of which official release, and more.
CVS clients for advanced source code manipulation
For additional information, see Common CVS Operations and Tips.