Git
Git is a distributed version control system invented by Linus Torvalds in April 2005 to replace BitKeeper for Linux kernel development. It was built from scratch because no existing free system met Torvalds’s strict criteria: sub-three-second patch application, distributed BitKeeper-like workflow, strong corruption safeguards, and rejection of CVS-style design. Git maintains a full local repository copy, uses SHA-1 hashing for object identification, and is grounded in a content-addressable filesystem model.