It is very hard to manage the project changes. Sometimes we need to
retreat our steps to find a better solution,- See what steps we took
earlier.
And for that we can use subversion tool. For linux it is a rpm to
install named "subversion".
This is the client tool. There is version for windows too. The home
page for the software is http://subversion.tigris.org/ .
And the most hard job here is to set up a server. To set up the
server you should read this,
http://svnbook.red-bean.com/en/1.0/ch06.html
-- Thanks Kamanashis Roy