The Revision Control System (RCS) is a tool that allows users to save the file modifications made over time. RCS allows users to store and retrieve versions of a file and allows users to associate information with each storing operation. The information associated to versions eases the task of retrieving versions and tracking changes to a file. Maintaining versions of files in RCS allows one to document the changes they have made to a file, for the benefit of themselves and their colleagues. Further, RCS provides features for handling groups of files, managing development among multiple individuals, and embedding and extracting version information in a working file, a version of the file currently available to the user. It is a powerful yet simple tool for tracking the changes made to files. RCS is an addition to the file system design helpful to those who work with files.