Emacs/W3 is a text-based web browser for the GNU Emacs text editor, written primarily by William M. Perry and entirely in GNU Emacs Lisp. Emacs/W3 is part of the Sumo package for XEmacs, and the submodule for fetching an URL is currently part of the GNU Emacs CVS repository.

As noted by the maintainer, the W3 package is currently monolithic and somewhat obsolete. A project has been proposed to reengineer W3 for increased modularity. More current Emacs web browsers include an interface to w3m.

Dave Raggett was supported by Emacs/W3 and by tkWWW while working on a successor to HTML 2 called HTML+.

Emacs ( /ˈiːmæks/) is a family of text editors, characterized by their extensibility. One manual describes it as "the extensible, customizable, self-documenting, real-time display editor." Development began in the mid-1970s and continues actively as of 2012^[update]. Emacs has over 2,000 built-in commands and allows the user to combine these commands into macros to automate work, in particular with the use of Emacs Lisp, a variant of Lisp, providing a deep extension capability.

The original EMACS consisted of a set of Editor MACroS for the TECO editor. It was written in 1976 by Richard Stallman, initially together with Guy L. Steele, Jr. It was inspired by the ideas of TECMAC and TMACS, a pair of TECO-macro editors written by Steele, Dave Moon, Richard Greenblatt, Charles Frankston, and others.

In Unix culture, Emacs became one of the two main contenders in the traditional editor wars, the other being vi. The word "emacs" is often pluralized as emacsen, by analogy with boxen (itself used by analogy with oxen) and VAXen.