Emacs

Emacs (), originally named EMACS (an acronym for "Editor Macros"), is a family of that are characterized by their extensibility. The manual for the most widely used variant, GNU Emacs, describes it as "the extensible, customizable, self-documenting, real-time display editor". Development of the first Emacs began in the mid-1970s, and work on GNU Emacs, directly descended from the original, is ongoing; its latest version is 31.1 , released 24 August 2026.

Emacs has over 10,000 built-in commands and its user interface allows the user to combine these commands into macros to automate work. Implementations of Emacs typically feature a dialect of the Lisp programming language, allowing users and developers to write new commands and applications for the editor. Extensions have been written to, among other things, manage files, remote access, e-mail, outlines, multimedia, Git integration, RSS feeds, and , as well as implementations of ELIZA, Pong, Conway's Life, Snake, Dunnet, and Tetris.

The original EMACS (an extensible, full-screen editor) was developed in 1976 at the MIT Artificial Intelligence Laboratory as a unified set of Editor MACroS (EMACS) for the . It was started by Guy L. Steele Jr. as a unification of the divergent TECO macro packages TECMAC and TMACS and was largely completed and extended by Richard M. Stallman, who is credited with naming it “Emacs” (and the “E” abbreviation) and with the core philosophy of real-time display editing and extensibility.

The most popular, and most ported, version of Emacs is GNU Emacs, which was created by Richard Stallman for the GNU Project. XEmacs is a variant that branched from GNU Emacs in 1991. GNU Emacs and XEmacs use similar Lisp dialects and are, for the most part, compatible with each other. XEmacs development is currently very slow.

GNU Emacs is, along with vi, one of the two main contenders in the traditional of Unix culture. GNU Emacs is among the oldest free and open source projects still under development.