To start with Source Code Configuration Management is basically tracking your source code with changes made to it. A consistent change will be recorded and can be kept track as a history. In this way there is no single copy of the file. Its maintained as change of change. This is how source code is maintained in any project in both open source and closed source.
"Maintaining code is equally important to writing good code"
Some of the source version control systems that I can think of are CVS, SVN, Perforce and some other commercial ones. I had worked with CVS and SVN extensively. :) In fact was introduced to SVN first and then asked to (cont...)