Unix history goes back to 1969 and the famous "little-used PDP-7 in a corner" on which Ken Thompson, Dennis Ritchie (the R in K&R) and others started work on what was to become Unix. The name "Unix" was intended as a pun on Multics (and was written "Unics" at first -- UNiplexed Information and Computing System). For the first 10 years, Unix development was essentially confined to AT&T's Bell Labs (prior to divestiture). These initial versions were labeled "Version n" or "Nth Edition" (of the manuals), and were for DEC's PDP-11 (16 bits) and later VAXen (32 bits).

UNIX's source code have been spread far and wide across our planet and many companies have developed their own versions.   One of the most famous versions is that developed at Berkeley.

UNIX is a multi-tasking OS that is used for a wide range of operations.

One of its drawbacks today for the common user is that it does not have a wide development of a Graphical User Interface (GUI) often referred to as Windows.  Many businesses have developed a GUI version for their own applications however, no general desktop version exists as yet as found with the Microsoft Windows products.

There are many UNIX web sites on the internet.  Use your search function for UNIX and you'll find more that you'll ever wanted.  Below are 2 good references to learn more.