Dr.Richard Matthew Stallman often known by his initials, RMS - is widely known as the father of the GNU and Free Software movement. He launched the GNU project in September 1983 with the goal of creating a Unix-like computer operating system composed entirely of free software. With this, he also launched the Free software movement. Richard Stallman has devoted the bulk of his life to political and social activism.
He is the main author of the copyleft license GNU General Public License (GPL) which allows you to use, modify, and distribute Free software published under the GPL license. The word “Free” means that all users have the freedom to study, share, change and improve the software. "Free" doesn't necessarily mean free as in free beer even though majority of the Free software is indeed free as in free beer too.
The most popular, and most ported, version of Emacs is GNU Emacs, which was created by Stallman for the GNU Project.
Official website of Richard M.Stallman - stallman.org
Home page of Free Software Foundation (FSF) - fsf.org