The GNU project (http://www.gnu.org/) was started by Richard Stallman in 1984 to create a complete free operating system and, in his words, "bring back the cooperative spirit that prevailed in the computing community in earlier days".
GNU is a recursive acronym for "GNU's Not Unix". However, as Unix was already in widespread use, and its overall architecture had proven technically sound, the GNU system was designed to be compatible with it. Components that were already freely available (like the TeX typesetting system and the X Window graphical system) would be adapted and reused; other software would be written from scratch.
To ensure that GNU software would remain free for all users "to run, copy, modify and distribute", the project would release it under a license designed to give everyone those permissions while preventing them from adding restrictions of their own. This idea, referred to as copyleft, was embodied in the GNU General Public License.
By 1990, the GNU system had an editor (Emacs), a compiler (GCC) and had reimplemented many of the core libraries and utilities of a standard UNIX distribution; all that was missing was the kernel. At this point, work commenced on the Hurd, the proposed GNU kernel.
The development of the Hurd quickly became mired in technical and personality conflicts. However, in 1991, Linus Torvalds wrote the Unix-compatible Linux kernel and released it under the GNU General Public licence. Linux was further developed by various programmers around the world and combined with the libraries and tools of the GNU system in 1992, and thus a fully functional free operating system was formed.
The Hurd is still in active development; an experimental version of the GNU system that uses the Hurd instead of Linux is now available.
Richard Stallman requests that GNU be pronounced guh-NEW "to avoid horrible confusion" with the word "new".
- http://groups.google.com/groups?hl=en&selm=771%40mit-eddie.UUCP -- Stallman's original 1983 announcement of the GNU project
- http://www.gnu.org/gnu/thegnuproject.html -- Stallman gives a lengthy personal account of the project and its history.
- http://www.gnu.org/encyclopedia/free-encyclopedia.html -- The Free Universal Encyclopedia and Learning Resource, Stallman's essay concerning a GNU encyclopedia.