Emacs is the extensible, customizable, self-documenting real-time display editor.

• Content sensitive major modes for a wide variety of file types, from plain text to source code to HTML files.
• Complete online documentation, including a tutorial for new users.
• Highly extensible through the Emacs Lisp language.
• Support for many languages and their scripts, including all the European ``Latin'' scripts, Russian, Greek, Japanese, Chinese, Korean, Thai, Vietnamese, Lao, Ethiopian, and some Indian scripts.
• A large number of extensions which add other functionality. The GNU Emacs distribution includes many extensions; many others are available separately--even a web browser