(BSD) A family of Unix versions for the DEC VAX and PDP-11, developed by Bill Joy and others at the University of California at Berkeley. BSD Unix incorporates paged virtual memory, TCP/IP networking enhancements, and many other features.

BSD UNIX 4.0 was released on 19 October 1980. The BSD versions (4.1, 4.2, and 4.3) and the commercial versions derived from them (SunOS, ULTRIX, Mt. Xinu, Dynix) held the technical lead in the Unix world until AT&T's successful standardisation efforts after about 1986, and are still widely popular.

See also Berzerkeley, USG Unix.