TortoiseSVN

TortoiseSVN is a free, open-source Windows client for the Apache Subversion (SVN) version control system. It runs as a Windows shell extension, so you run Subversion commands from the Windows Explorer context menu. Icon overlays on files and folders show each item's status, such as normal, modified, or conflicted. It works with any development tools and any type of file, and it doesn't need the Subversion command line client.