GNU/Linux is the term used by the Free Software Foundation and its supporters (especially it's founder and main activist Richard Stallman) to refer to what is more commonly called the Linux operating system. The software originally written by Linus Torvalds is not actually a complete operating system, but rather a Unix-like kernel. Linus and other early Linux developers adapted most of the available GNU software to work with Linux, and thus a completely functional operating system was formed. Since the GNU project was begun to develop such an operating system, and all of the elements of the GNU system except for the kernel were built by the Free Software Foundation, Stallman argues that the system is more properly called GNU/Linux. The FSF also point to the development of the Hurd kernel; an effort to complete the GNU system with its own kernel (although under the GPL licence, Linux is technically not part of the GNU project).
The various reasons people refer to the system as simply "Linux" are:
- It is shorter and thus easier to say.
- Some consider the term "operating system" to refer to only the kernel, while the rest are simply utilities (regardless of the practical necessity of such utilities). Thus the operating system is Linux, and a Linux distribution is based on Linux with the addition of the GNU tools.
- The creator of the Linux kernel, Linus Torvalds, has referred to the combined system solely as Linux from the time of its initial release in 1991.
- Only when Richard Stallman and the Free Software Foundation began asking people in the mid 1990s (after the system had become popular) to call the system GNU/Linux did the question arise. The corporate world, most media outlets and many users and programers in the open source community have ignored or opposed his campaign and have kept calling it Linux.
http://www.gnu.org/gnu/linux-and-gnu.html -- Linux and the GNU Project, by Richard Stallman
http://www.slashdot.org/articles/99/04/09/1516203.shtml -- A Slashdot debate on the name issue