Concurrent versions system is an open-source software configuration management utility designed to manage different versions of the same software project in a specialized repository. Concurrent versions system CVS is accessible a program that lets to code developer save and retrive different development versions of source code. CVS works not by keeping track of multiple copies of source code files,but by maintain a copy and a record of all the changes.When a developer specifies a particular versions, CVS is typically used to keep track of each developers work individually in a separate working directory.CVS uses a client-server a server stores the current versions of a project, and client connect to the server in order to check out a complete . The server will only accept changes made to the most recent version of a file . CVS enable a multiple developers to works simulationlay on a single file without loss a data . CVS can be integreted in bug tracking and feature tracking system. To CVS find bug in server CVS can be used many environment for many purposes.It is used for maintaining configuration files, mail , source code , FAQ file . A version control system can enables you to retrieving changes in most version control on systems note of each changes , and many provides tools . Most includes the ability to retrieve different between arbitray varsions of files which makes to easy to create bugs.More benefits of a version control system for any stored revision of a file can be retriveing to be viewed or changed .The differences between any two CVS revisions can be displayed. Another way highly in valuable features is the ability to revert to earlier version where you may want make modification certain features of your software.