The GNU Project is the free software project launched by stallman in 1983 with the announcement-of-gnu-project. Its goal was to create a complete free operating system — GNU, a recursive acronym for "GNU's Not Unix" — that would give users all four-freedoms: to run, study, redistribute, and improve the software.
The gnu-manifesto (1985) articulated the philosophical and practical rationale for the project. GNU would be Unix-compatible but entirely free software, licensed under gpl-v1 and its successors to ensure that copyleft — the legal mechanism described in gpl-copyleft-mechanism — would prevent the software from being made proprietary.
By the early 1990s, the GNU Project had produced most of the components of a complete operating system: the Emacs text editor (see gnu-emacs-first-release), GCC (the GNU Compiler Collection), the GNU C Library, and many utilities. The missing piece was the kernel, GNU Hurd, which was never completed.
In 1991, linus-torvalds released the Linux kernel under gpl-v2, providing the missing component. The resulting combination is what stallman insists be called "GNU/Linux" — the gnu-linux-naming controversy — arguing that Linux completed the GNU system rather than being an independent creation.
The GNU Project is administered by the free-software-foundation and remains active. It has produced foundational software including GCC, GDB, Bash, GNU Make, and Emacs. The project's relationship with the broader open-source community is shaped by the tension between software-freedom-vs-open-source that defines Stallman's conflict with eric-raymond and the open-source-initiative.