Emacs and its derivatives are a family of
text editors that are characterized by their
extensibility. The manual for the most widely used variant,
GNU Emacs, describes it as "the extensible, customizable, self-documenting, real-time display editor". Development of the first Emacs began in the mid-1970s and continues actively . Emacs has over 2,000 built-in commands and allows the user to combine these commands into
macros to automate work.
Emacs Lisp provides a deep extension capability allowing users and developers to write new commands using a dialect of the
Lisp programming language.