"Imagine a utility that lets you make an annotated backup of any of your project files with the click of a mouse or a single command. It would let you review the history of your backups and recover any version you wished. And it would integrate with your file browser and would keep track of files that have changed since your last backup. The utility exists--Subversion, and its companion program TortoiseSVN, can help you safely manage your files as you work with them.
"Subversion is one of a class of programs that has been used by programmers for decades: the source code control system, which developers use to manage changes to program source code. Such software has features that enable large teams to work in a distributed environment on the same files while keeping track of who has done what, and when..."
