Richard Stallman Begins Work on GNU
January 5, 1984
Richard Stallman begins work on the GNU operating system, intended to be a free UNIX-like OS. Combined with the Linux kernel, GNU/Linux is the most popular free and open-source operating system today. Believing that people should be able to freely modify the software they use, Stallman would later found the Free Software Foundation and write the GNU GPL, the most popularly used free software license.