UNIX (which doesn't really stand for anything), is the trademarked name of the multi-user, multi-tasking, time-sharing operating system developed at AT&T's Bell Labs in 1969. Many web sites are maintained on UNIX systems. While technically the name UNIX refers to only a few trademark-licensed versions, it is often used to refer to the many versions currently available on the market. The differences to the user are slight.

UNIX was originally designed on a "spare" minicomputer, to allow some folks to have a quick time-sharing system to simplify their documentation procedures. The moniker UNIX was given to it by the somewhat sarcastic users of the huge mainframes prevalent in those days -- pointing out that they considered it to be a somewhat underpowered operating system.

AT&T commercially released UNIX in the early 1970's. By the late '70s, the University of California, Berkeley had developed its own version, called BSD (for Berkeley Software Distribution), which it offered for free to other colleges and universities.

Because it could run on many different computer platforms, it quickly became the platform of choice for many researchers and students. Since networking and e-mail are both integral to UNIX, it was easy for two or more UNIX computers to "talk" to each other. That is why by the late 1980's, UNIX ran on almost every machine on the Internet. In fact, the Internet's protocols were developed on UNIX machines, for UNIX machines. For example, Usenet, the loose confederation of computers that exchanges newsgroups and electronic mail by passing messages back and forth, was based almost exclusively on UNIX machines.

UNIX now runs on every hardware platform from PC and Macintosh to high-performance graphical workstations to multimillion dollar supercomputers. The big difference between versions and platforms is that the more expensive platforms run faster or support more simultaneous users.