A repository is a persistent store that coordinates multi-user access to projects and their contents. Projects in a repository can be of two forms: immutable (a project version) or modifiable (project in a stream). Communication between the repository and workbench clients is possible over local or wide area networks.
Currently, the workbench supports one type of repository, the Concurrent Versions System (CVS). Currently the workbench supports two authentication protocols; pserver and ssh.
You can find more information at http://www.cvshome.org.