This document provides an overview and comparison of various source control systems, including Subversion (SVN), Git, Bazaar (Bzr), and Mercurial (Hg). It discusses features of centralized and distributed version control systems. Key centralized systems include SVN, while distributed systems include Git, Bzr, and Hg. The document compares aspects like creators, users, licenses, and documentation quality. It also covers concepts like local repositories, snapshots vs changesets, and branching in distributed version control. Hosted code solutions and social coding aspects are briefly outlined.