Version control allows you to keep track of changes you make to scripts.  It’s like a supercharged backup system.  Each time you make changes and check in you have a new “version”.  Make a mistake or need to “back out” a change and it is possible to go back to a previous version.

Here’s the original article:

http://www.mjtnet.com/blog/2007/10/26/version-control-for-your-scripts/