The GNU project (GNU is Not Unix - recursive acronym) was created by Richard Stallman in 1984, with the purpose of developing a completely free Unix system. Its first projects laid the foundations for the development of free software: the Emacs editor and the GCC compiler.
Hundreds of software applications have now been developed by this organisation of many unpaid volunteers. In the long run GNU aims to provide a complete system, especially by the development of the futuristically designed Hurd kernel launched over ten years ago. GNU tools provide a large part of the Linux distributions. This includes the version control system CVS, shell bash and wget, the file retrieval software.
The GNU project is probably the main pillar of the free software movement. This is why the Free Software Foundation is highly respected within the free software community. All the GNU tools are of course under GPL (GNU General Public License) licence.