From Citizendium, the Citizens' Compendium
- Operating system : The main software of a computer system; controls the execution of applications and provides various services to them.
- Unix directory structure : A convention of the organization of the directory structure in Unix-like operating systems.
- Berkeley Software Distribution : Free Unix distribution created by the University of California at Berkeley.
- Linux : A free and open source operating system kernel designed by Linus Torvalds. The kernel is typically augmented by a plethora of other software, creating a Linux distribution.
- Mac OS X : BSD-based, POSIX-compatible graphical Unix operating system made by Apple for use on Macintosh computers.
- POSIX : Add brief definition or description