GNU is a recursive acronym for “GNU’s Not Unix!”, chosen because GNU’s design is Unix-like, but differs from Unix by being free software and containing no Unix code. The GNU project includes an operating system kernel, GNU HURD, which was the original focus of the Free Software Foundation (FSF). However, non-GNU kernels, most famously Linux, can also be used with GNU software; and since the kernel is the least mature part of GNU, this is how it is usually used. The combination of GNU software and the Linux kernel is commonly known as Linux (or less frequently GNU/Linux; see GNU/Linux naming controversy).
Development of the GNU operating system was initiated by Richard Stallman at the Massachusetts Institute of Technology (MIT) Artificial Intelligence Laboratory as a project called the GNU Project which was publicly announced on September 27, 1983, on the net.unix-wizards and net.usoft newsgroups by Richard Stallman.
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