[Links to source and .pdf under "read more"]

GNU Emacs is much more than a text editor; over the years, it has expanded to become an entire workflow environment, impressing programmers with its integrated debugging and project-management features. It is also a multi-lingual word processor, can handle all your email and Usenet news needs, display web pages, and even has a diary and a calendar for your appointments!

Features include:

Special editing modes for 27 programming languages, including C, C++, Fortran, Java, JavaScript, Lisp, Objective C, Pascal, Perl, and Scheme.
Special scripting language modes for Bash, other common shells, and creating Makefiles for GNU/Linux, UNIX, Windows/DOS, and VMS systems.
Support for typing and displaying in 60 non-English languages, including Arabic, Chinese, Czech, Hebrew, Hindi, Japanese, Korean, Russian, Vietnamese, and all Western European languages.

The ability to:
Create PostScript output from plain-text files (special editing modes for LaTeX and TeX are included).
Compile and debug from inside Emacs.
Maintain program ChangeLogs.
Flag, move, and delete files and sub-directories recursively (directory navigation).
Run shell commands from inside Emacs, or even use Emacs itself as a shell (Eshell).
Enjoy the use of extensive merge and diff functions.
Take advantage of built-in support for many version control systems, including Git, Bazaar, Mercurial, Subversion, and CVS.
And much more!

Source files for GNU Emacs Manual, as well as a downloadable PDF version, are found here: https://www.gnu.org/software/emacs/manual/emacs.html

About the original and principal author:

Richard M. Stallman developed the first Emacs in 1976 and wrote GNU Emacs in 1984/85. He has received the ACM Grace Hopper Award, a MacArthur Foundation fellowship, the Electronic Frontier Foundation's Pioneer award, the Takeda Award for Social/Economic Betterment, and the ACM Software and System Award, as well as several doctorates honoris causa.