BSD

Berkeley Software Distribution (BSD, sometimes called Berkeley Unix) is the UNIX derivative distributed by the University of California, Berkeley, starting in the 1970s.

Historically, BSD has been considered as a branch of UNIX — 'BSD UNIX', because it had shared the initial codebase and design with the original UNIX by AT&T and collaborated on the development in the pioneer days of UNIX. It was widely identified with the versions of UNIX available for workstation-class systems, that can be attributed to the ease with which it could be licensed and the familiarity it found among the founders of many technology companies during the 1980s. The familiarity often came from using similar systems — notably DEC's ULTRIX and Sun Microsystems SunOS — during their education. Though BSD itself was largely superseded by the System V Release 4 and OSF/1 systems in the 1990s (both of which incorporated BSD code), the modified codebase as open source — mostly derived from 4.4BSD-Lite have seen increasing use and development recently.

Today, the term of "BSD" is often non-specifically used to refer to any of the BSD descendants, e.g. FreeBSD, NetBSD or OpenBSD, which forms a branch of Unix-like operating systems.