Apache Subversion (often abbreviated SVN, after the command name svn) is a software versioning and a revision control system distributed under a free license. Developers use Subversion to maintain current and historical versions of files such as source code, web pages, and documentation. Its goal is to be a mostly-compatible successor to the widely used Concurrent Versions System (CVS).
The open source community has used Subversion widely: for example in projects such as Apache Software Foundation, Free Pascal, FreeBSD, GCC, Django, Ruby, Mono, SourceForge, PHP and MediaWiki. Google Code also provides Subversion hosting for their open source projects. BountySource systems use it exclusively. CodePlex offers access to Subversion as well as to other types of clients.
One important feature of the Subversion filesystem is properties: simple name=value pairs of text. Properties occur in two different places in the Subversion filesystem. The first is on filesystem entries (i.e., files and directories). These are versioned just like other changes to the filesystem. Users can add any property they wish, and the Subversion client uses a set of properties, which it prefixes with 'svn:'.