Source Code Control With Top

How does a TOP developer handle source code control? By source code control I mean: the management of changes made to the code. How are different versions maintained? Branching ever allowed? Merging? I'm not really talking about the source code itself, I'm asking how you maintain it and all its versions. Personally, I like to have the option that when I do something stupid I am able to rollback to a previous version and start over.

See: SourceCodeInDatabase