Richard M. Stallman (RMS) is the founder of the GNU project and the Free Software Foundation. He is the brains behind the GNU General Public License (GPL). The GNU GPL is used in the GNU/Linux operating system, and in other popular software. Stallman was part of MIT's Artificial Intelligence Laboratory in the 1970s, where he did a lot of creative computer programming (which he and his friends called "hacking").
He conceived of a notion of "free software" where the software is free as in "free speech", as opposed to "free beer", as he explains it. It is formally licensed as an alternative to the public domain and to other free licenses. He as actively promoted forming a worldwide community of programmers and software users who can all equally share the benefits of new and improved software donated to the community, a sort of communism of software development, enforced through a subversive use of "copyleft" copyright licenses.
Stallman's political and religious views
Stallman is also an atheist, and his website espouses a number of radical liberal political viewpoints; while he refers to himself as "Liberal", some, in fact, suspect that he is a communist, as he even criticized Barack Obama for being too conservative. He has also dealt with the communist governments of Cuba and Venezuela, seeking to convince them to utilize open source software. He also openly states his opposition to Christianity (and religion in all of its forms), an action condemned by many.
Stallman sees fit to blaspheme the Lord and His Church, claiming to be a saint, Saint IGNUcius, in his mock Church of Emacs.
Stallman was diagnosed with autism. See Atheism and autism.