Use open source Subversion for personal document management
There is an open source version control system, or revision control system, known as Subversion (svn for short) that has rapidly become a favorite of developers. It enjoys an excellent reputation and a wealth of free, online documentation, as well as a growing body of published texts on the subject of its efficient and practical use. It is stable, flexible, capable, security-conscious, free, open source software, and scales well for any size project.
The previous king of open source version control was CVS, the Concurrent Versioning System. Subversion began as an attempt to build upon the solid, respected foundation of the venerable CVS, and to improve upon it based on the lessons of years of widespread CVS use. It has succeeded in all respects, if its ever-growing popularity is any indication.
Thanks in part to the nearly transparent use of Subversion, the high number of available client applications across a number of operating system platforms for it, and Subversion's low overhead and ease of administration, version control isn't just for source code anymore.