What is GNU?
The GNU Project, pronounced "guh-noo", was launched in 1984 to develop a complete UNIX style operating system which is comprised of free software: the GNU system. Variants of the GNU operating system, which use the Linux kernel, are now widely used; though these systems are often referred to as "Linux," they are more accurately called GNU/Linux systems.
The GNU project is closely linked to the philosophy of free software, which is central to the projects that derive from it, such as Ubuntu. The concept of free software is explained at the section called "Free Software".