In addition to UNIXgod's comment, I can refer you to: http://en.wikipedia.org/wiki/OS_X http://en.wikipedia.org/wiki/OS_X There you will find: http://en.wiki

In addition to UNIXgod's comment, I can refer you to: http://en.wikipedia.org/wiki/OS_X http://en.wikipedia.org/wiki/OS_X There you will find: http://en.wikipedia.org/wiki/Comparison_of_BSD_operating_systems http://en.wikipedia.org/wiki/Comparison_of_BSD_operating_sys... "... Apple Inc.'s iOS and Mac OS X, with its Darwin base including a large amount of code derived from FreeBSD." http://en.wikipedia.org/wiki/Darwin_(operating_system) http://en.wikipedia.org/wiki/Darwin_(operating_system) "Darwin is an open source POSIX-compliant computer operating system released by Apple Inc. in 2000."