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.
- Free software : Software that can be used, studied, and modified without restriction; and redistributed under these terms.
- GNU/Linux : An operating system consisting of the Linux kernel and GNU utilities.
- Linux naming controversy : A dispute between the Free Software Foundation and various Linux-supporting groups over the naming of operating systems that are based on the Linux kernel and use GNU utilities.