Here is some trivia for those who enjoy that kind of thing. Unix was written by some men who had just worked on the Multics project. They had become addicted to a game and needed a system to play it on. The term Unix is not an acronym and shouldn't really be capitalized. It's a joking reference to Multics. The man who coined the term has given up arguing about it. AT&T got the rights and granted free use to academic institutions. When the project at Berkeley was closed, some of the members founded Berkeley Software Development (BSD). AT&T raised a fuss about that but it's long since been settled. There are several BSD variants, one of which claims it's never been hacked. FreeBSD, by far the most popular, is the basis of OS X. Linux is nothing but a kernel; sort of a glorified BIOS that controls how the CPU is used. The utilities that make up the rest of the system are provided by Richard Stallman's (paid for with a McArthur genius grant) GNU (gnu's not unix. They love stupid recursive jokes.) Foundation, which is also writing a kernel.