Subversion is a free/open-source revision control system (RCS). That is, Subversion manages files and directories over time. These files and directories are placed into a central storage called repository. The repository is quite similar to a ordinary file server, except that it remembers every change ever made to your files and directories. This allows one to recover older versions of your data, or examine the history of how your data changed. The software is released under an Apache/BSD-style open source license.