Linux

Linux ('Linus Unix', unofficial recursive backronym: Linux Is Not Unix) is a Unix-like kernel, which is more similar to the Unix System V family instead of the BSD family of Unixes. Its development was started in 1991 by Linus Torvalds, who was inspired by Tanenbaum's MINIX operating system.

Nowadays, Linux has seen popular use in server environments as a replacement for expensive and (often) outdated Unix operating systems. However, desktop market share is low, but steadily increasing.