Unix

Originally developed in the 1970s by Bell Labs, Unix is one of the most powerful, most stable, and most influential computer operating systems ever created as many of its features have been plagiarized throughout the years to be incorporated into other systems.

Mac OS X

iOS

Unix.org

FreeBSD A free version of Unix for Intel platforms.

Solaris (Oracle) A popular Unix OS created originally by Sun Microsystems

SCO OpenServer (SCO Group) Closed source Unix, once popular on i386-based computers.

Mac OS X Apple's famous Mac OS X, based on BSD Unix.

iOS Apple's iOS for use with Apple's handheld devices such as the iPhone, iPod, and iPad.

Wikipedia