Mercurial

Mercurial is a free, distributed source control management tool. It offers you the power to efficiently handle projects of any size while using an intuitive interface. It is easy to use and hard to break, making it ideal for anyone working with versioned files.

Traditional version control systems such as Subversion are typical client-server architectures with a central server to store the revisions of a project. In contrast, Mercurial is truly distributed, giving each developer a local copy of the entire development history. This way it works independent of network access or a central server. Committing, branching and merging are fast and cheap.

Mercurials implementation and data structures are designed to be fast. You can generate diffs between revisions, or jump back in time within seconds. Therefore Mercurial is perfectly suitable for large projects such as OpenJDK (hg) or NetBeans (hg).