"On September 27, 1983, a computer scientist named Richard Stallman announced the plan to develop a free software Unix-like operating system called GNU, for "GNU's not Unix." GNU is the only operating system developed specifically for the sake of users' freedom, and has remained true to its founding ideals for forty years. Since 1983, the GNU Project has provided a full, ethical replacement for proprietary operating systems. This is thanks to the forty years of tireless work from volunteer GNU developers around the world." https://www.fsf.org/news/forty-years-of-gnu-and-the-free-software-movement Though there is a lot of politics in naming this "The GNU operating system" - "In 1992, the essential components of GNU were complete, except for one, the kernel. When in 1992 the kernel Linux was re-released under the GNU GPL, making it free software, the combination of GNU and Linux formed a complete free operating system, which made it possible for the first time to run a PC without non-free software. This combination is the GNU/Linux system." https://www.gnu.org/gnu/gnu-linux-faq.html