HISTORY
The Unix operating system was conceived and implemented in the 1960s and first released in 1970. Its wide availability and portability meant that it was widely adopted, copied and modified by academic institutions and businesses, with its design being influential on authors of other systems.

The GNU project, started in 1984 by Richard Stallman, had the goal of creating a "complete Unix-compatible software system" composed entirely of free software. The next year Stallman created the Free Software foundation,and wrote the GNU Public Lisence (GNU GPL) in 1989. By the early 1990s, many of the programs required in an operating system (such as libraries,compilers, text editors, a Unix Shell and a windowing system) were completed, although low-level elements such as device drivers, deamons, and the kernel were stalled and incomplete. Linus Torvalds has said that if the GNU kernel had been available at the time (1991), he would not have decided to write his own.

MINIX
In 1991 while attending the University of Helsinki, Torvalds began to work on a non-commercial replacement for MINUX, which would eventually become the Linux Kernel.

Linux was dependent on the MINIX user space at first. With code from the GNU system freely available, it was advantageous if this could be used with the fledgling OS. Code licensed under the GNU GPL can be used in other projects, so long as they also are released under the same or a compatible license. In order to make the Linux kernel compatible with the components from the GNU Project, Torvalds initiated a switch from his original license (which prohibited commercial redistribution) to the GNU GPL. Developers worked to integrate GNU components with Linux to make a fully functional and free operating system.