Emacs is the advanced, extensible, customizable, self-documenting editor.

The features of GNU Emacs include:

• Content-aware editing modes, including syntax coloring, for many file types.
• Complete built-in documentation, including a tutorial for new users.
• Full Unicode support for nearly all human scripts.
• Highly customizable, using Emacs Lisp code or a graphical interface.
• A wide range of functionality beyond text editing, including a project planner, mail and news reader, debugger interface, calendar, IRC client, and more.
• A packaging system for downloading and installing extensions.