Emacs

Emacs is a family of cross-platform text editors renowned for their extensibility. The most widely used variant is GNU Emacs; there have been other forks such as XEmacs. The project name Emacs stands for Editing MACroS, a reference to its macro-based extensibility.

Emacs originated in the 1970s as a set of macros for the TECO editor, created by Richard Stallman and Guy L. Steele Jr. The GNU Project launched GNU Emacs in 1985 as a free, Lisp-based editing environment. Since then, it has been ported to many operating systems and fostered a large ecosystem of extensions.

Key features include a built-in Lisp interpreter (Emacs Lisp) that lets users customize commands, define new editing operations, and write programs. It supports multiple buffers, extensive undo, powerful search and replace, and integration with compilers, debuggers, and version-control systems. A flexible packaging system (ELPA/MELPA) makes it easy to install thousands of extensions. Emacs also includes a number of integrated tools for mail, news, calendars, and project navigation, and has popular distributions such as Spacemacs and Doom Emacs.

Usage in Emacs emphasizes keyboard-driven operation, with many commands bound to Control and Meta keys, though it offers menus and mouse support. It remains widely used by programmers, writers, and researchers for programming in languages such as Lisp, C, Python, and many others.

Emacs is released under the GNU General Public License, and is free software.