Git

Git is a free and open source distributed version control system designed to handle everything from small to very large projects with speed and efficiency. Git is easy to learn and has a tiny footprint with lightning fast performance. It outclasses SCM tools like Subversion, CVS, Perforce, and ClearCase with features like cheap local branching, convenient staging areas, and multiple workflows.

Books

Ry’s Git Tutorial
Pro Git
Learn Version Control with Git
Learn Enough Git to Be Dangerous
A Guide to Git and Github
Git Pocket Guide
Git from the Bottom Up