It is a set of UNIX commands that allow multiple users to develop and maintain program code or documents.

RCS was originally developed for programs but is also useful for text documents or configuration files that are frequently revised.

[9] Redistribution and use in source and binary forms are permitted provided that the above copyright notice and this paragraph are duplicated in all such forms and that any documentation, advertising materials, and other materials related to such distribution and use acknowledge that the software was developed by Walter Tichy.RCS 4.3, released 26 July 1990, was distributed "under license by the Free Software Foundation", under the terms of the GPL.

[4] RCS revolves around the usage of "revision groups" or sets of files that have been checked-in via the co (checkout) and ci (check-in) commands.

Once checked in, RCS stores revisions in a tree structure that can be followed so that a user can revert a file to a previous form if necessary.