GNU Emacs is an extensible, customizable, self-documenting real-time display editor. At the core of Emacs lies an Emacs Lisp interpreter, the language in which the majority of Emacs' built-in functionality and extensions are implemented. Also consider asking your question at emacs.stackexchange.com.
GNU Emacs is an extensible, customizable text editor. Begun in the mid-1970s as TECO, it was re-written using C and Emacs Lisp to provide portability and an extendable interface. It continues to be actively developed today.
Emacs provides context-sensitive editing modes with syntax coloring, is self documenting, has full Unicode support and extensions to do almost anything. Die-hard Emacs users do most everything from within Emacs: write, compile, run and debug code; read/compose email; browse the web; do project planning etc.
Notice that there are several popular Mac versions of Emacs (and probably still more unpopular ones! :-)
When asking about Emacs, please specify which package you are using. The URL where you downloaded it is often a good enough indication.
- https://emacsforosx.com/ provides a straightforward packaging of GNU Emacs for macOS.
- https://aquamacs.org/ provides a version which attempts to adapt GNU Emacs to macOS conventions (though the Aqua UI which the name alludes to is long gone).
- Homebrew offers an Emacs recipe
- A paper by Richard Stallman describing the design of Emacs
- The Emacs Wiki, a collaborative wiki for extensions to Emacs
- Wikipedia's Emacs page
- History of Emacs and GPL
- GNU Emacs homepage