Git

Git is a distributed source version control tool.

Martin Fowler mentions it in his blog post, where he describes his thoughts on the topic. There's a lot of good links in that post. Here are a few more useful ones...

Git - SVN Crash Course

Git home page

git faq

Git Community Book - the heart of documentation,

Git User Manual,

and, of course, TortoiseGit download page.

 

If you’d like to use git in a fashion similar to CVS (or SVN), read gitcvs-migration.

Also, here is the link to Mercurial home.