Mercurial Version Control

Mercurial is a free, distributed source control management tool designed for efficient handling of very large projects. Created by Matt Mackall in 2005 in response to BitKeeper license changes, Mercurial is used by Mozilla Firefox, Facebook, Nginx, and Python. Key features: distributed architecture where every clone is a full repository with complete history, enabling offline work and fast local operations. Written in Python with C extensions, running on Linux, macOS, Windows, and BSD. Efficient append-only revlog storage using delta compression for fast history access and minimal disk usage. Named branches for long-lived development streams and bookmarks for lightweight Git-like branching. MQ Mercurial Queues for patch management, maintaining stacks of patches for upstream contribution. Phases (public, draft, secret) for tracking shared, mutable, or private changesets. Evolve extension for safe history rewriting with obsolete markers. Server-side browsing via hgweb, plus RhodeCode and Kallithea for hosted repositories. TortoiseHg Windows shell integration and standalone GUI with visual diff and merge. Over 200 built-in and community extensions including histedit, rebase, and largefiles. Pre and post transaction hooks for automation including commit validation and CI triggering. Simple commands (hg add, hg commit, hg push, hg pull) with comprehensive help. Performance optimized for repositories with millions of revisions.