Git is a version control system created by Linus Torvalds for development of the Linux kernel. It's pretty good, although the interface is a bit rough.
Interesting Links
- Tom Werner-Preston's The Git Parable, a fictionalised version of the problems that led to git being designed the way it is
- So You Think You Know Git, a talk on more niche Git usage by Scott Chacon. Almost ever 2 mins could have a page in Problems