The GNU operating system is a complete free software system, upward-compatible with Unix. GNU stands for “GNU’s Not Unix”. Richard Stallman made the Initial Announcement of the GNU Project in September 1983. A longer version called the GNU Manifesto was published in March 1985. It has been translated into several other languages. The name “GNU” was chosen because it met a few requirements; first, it was a recursive acronym for “GNU’s Not Unix”, second, because it was a real word, and third, it was fun to say (or Sing). The word “free” in “free software” pertains to freedom, not price. You may or may not pay a price to get GNU software. Either way, once you have the software you have four specific freedoms in using it. The freedom to run the program as you wish; the freedom to copy the program and give it away to your friends and co-workers; the freedom to change the program as you wish, by having full access to source code; the freedom to distribute an improved version and thus help build the community. (If you redistribute GNU software, you may charge a fee for the physical act of transferring a copy, or you may give away copies.)
The project to develop the GNU system is called the “GNU Project”. The GNU Project was conceived in 1983 as a way of bringing back the cooperative spirit that prevailed in the computing community in earlier days—to make cooperation possible once again by removing the obstacles to cooperation imposed by the owners of proprietary software.
In 1971, when Richard Stallman started his career at MIT, he worked in a group which used free software exclusively. Even computer companies often distributed free software. Programmers were free to cooperate with each other, and often did.
By the 1980s, almost all software was proprietary, which means that it had owners who forbid and prevent cooperation by users. This made the GNU Project necessary.
Every computer user needs an operating system; if there is no free operating system, then you can’t even get started using a computer without resorting to proprietary software. So the first item on the free software agenda obviously had to be a free operating system.
We decided to make the operating system compatible with Unix because the overall design was already proven and portable, and because compatibility makes it easy for Unix users to switch from Unix to GNU.
A Unix-like operating system includes a kernel, compilers, editors, text formatters, mail software, graphical interfaces, libraries, games and many other things. Thus, writing a whole operating system is a very large job. We started in January 1984. The Free Software Foundation was founded in October 1985, initially to raise funds to help develop GNU.
By 1990 we had either found or written all the major components except one—the kernel. Then Linux, a Unix-like kernel, was developed by Linus Torvalds in 1991 and made free software in 1992. Combining Linux with the almost-complete GNU system resulted in a complete operating system: the GNU/Linux system. Estimates are that tens of millions of people now use GNU/Linux systems, typically via GNU/Linux distributions. The principal version of Linux now contains non-free firmware “blobs”; free software activists now maintain a modified free version of Linux, called Linux-libre.
However, the GNU Project is not limited to the core operating system. We aim to provide a whole spectrum of software, whatever many users want to have. This includes application software. See the Free Software Directory for a catalogue of free software application programs.
We also want to provide software for users who are not computer experts. Therefore we developed a graphical desktop (called GNOME) to help beginners use the GNU system.
We also want to provide games and other recreations. Plenty of free games are already available.
How far can free software go? There are no limits, except when laws such as the patent system prohibit free software. The ultimate goal is to provide free software to do all of the jobs computer users want to do—and thus make proprietary software a thing of the past.
Herhangi bir işletim sistemi normal yollarla önyükleme yapamadığında kullanıcıya yardımcı olması amacıyla tasarlanan 
21.1 sürümü 
UNIX türevi işletim sistemleri için bir 
Debian projesi;