1. /ee'maks/ n. [from Editing MACroS] The ne plus ultra of hacker editors, a programmable text editor with an entire LISP system inside it. It was originally written by Richard Stallman in TECO under ITS at the MIT AI lab; AI Memo 554 described it as "an advanced, self-documenting, customizable, extensible real-time display editor". It has since been reimplemented any number of times, by various hackers, and versions exist that run under most major operating systems. Perhaps the most widely used version, also written by Stallman and now called "GNU EMACS" or GNUMACS, runs principally under Unix. (Its close relative XEmacs is the second most popular version.) It includes facilities to run compilation subprocesses and send and receive mail or news; many hackers spend up to 80% of their tube time inside it. Other variants include GOSMACS, CCA EMACS, UniPress EMACS, Montgomery EMACS, jove, epsilon, and MicroEMACS. (Though we use the original all-caps spelling here, it is nowadays very commonly `Emacs'.) Some EMACS versions running under window managers iconify as an overflowing kitchen sink, perhaps to suggest the one feature the editor does not (yet) include. Indeed, some hackers find EMACS too heavyweight and baroque for their taste, and expand the name as `Escape Meta Alt Control Shift' to spoof its heavy reliance on keystrokes decorated with bucky bits. Other spoof expansions include `Eight Megabytes And Constantly Swapping' (from when that was a lot of core), `Eventually malloc()s All Computer Storage', and `EMACS Makes A Computer Slow' (see recursive acronym). See also vi. From Jargon Dictionary

2. A UNIX-based text editor that is sometimes configured as the default editor on UNIX systems. Programmed in LISP, emacs is an excellent hacker's tool, but can be a nightmare for users accustomed to user-friendly word processing programs. From QUECID

3. Emacs is different things to different people. Depending who you ask, you'll could get any of the following responses: Text Editor, Mail Client, News Reader, Word Processor, Religion, Integrated Development Environment, Whatever you want it to be!, But for our purposes, let's just pretend it's a text editor--an amazingly flexible text editor. We'll dig deeper into the question later on. Emacs was written by Richard Stallman (founder of the Free Software Foundation: http://www.fsf.org/ and the GNU project http://www.gnu.org/) and he still maintains it today. Emacs is one of the most popular and powerful text editors used on Linux (and Unix). It is second in popularity only to vi. It is known for it huge feature set, ability to be easily customized, and lack of bugs. It's large feature set and ability to be customized actually are the result of how Emacs was designed and implemented. Without going into all the details, I'll simply point out that Emacs isn't ``just an editor''. It is an editor written mostly in the programming language Lisp. At the core of Emacs is a full-featured Lisp interpreter written in C. Only the most basic and low-level pieces of Emacs are written in C. The majority of the editor is actually written in Lisp. So, in a sense, Emacs has an entire programming language ``built in'' which you can use to customize, extend, and change its behavior. Emacs is also one of the oldest editors around. The fact that is has been used by thousands of programmers over the past 20 (?) years means that there are many add-on packages available. These add-ons allow you to make Emacs do things that Stallman had probably never dreamed possible when he first began work on Emacs. More on that in a later section. There are many other web sites and documents which give a better overview of Emacs, its history, and related matters. Rather than attempt to reproduce much of that here, I suggest that you check out some of the places listed in Section Other Resources section of this document. From EMACs-HOWTO

4. The extensible, customizable, self-documenting real-time display editor. Emacs has special code editing modes, a scripting language (elisp), and comes with many packages for doing mail, news. From Linux Guide @FirstLinux

5. Emacs is a powerful, customizable, self-documenting, modeless text editor. Emacs contains special code editing features, a scripting language (elisp), and the capability to read mail, news and more without leaving the editor. This package includes the libraries you need to run the Emacs editor, so you need to install this package if you intend to use Emacs. You also need to install the actual Emacs program package (emacs-nox or emacs-X11). Install emacs-nox if you are not going to use the X Window System; install emacs-X11 if you will be using X. From Mandrake 9.0 RPM

6. Emacs is a powerful, customizable, self-documenting, modeless text editor. Emacs contains special code editing features, a scripting language (elisp), and the capability to read mail, news, and more without leaving the editor. From Redhat 8.0 RPM