Berkeley Software Distribution (BSD,
sometimes called Berkeley Unix) is the Unix derivative distributed by the
University of California, Berkeley, starting in the 1970s. The name is also used
collectively for the modern descendants of these distributions.
A D V E R T I S E M E N T
BSD was widely identified with the versions of Unix available for
workstation-class systems. This 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. This familarity often came from using
similar systems—notably DEC's Ultrix and Sun's SunOS—during their education.
While BSD itself was largely superseded by the System V Release 4 and OSF/1
systems in the 1990s (both of which incorporated BSD code), in recent years
modified open source versions of the codebase (mostly derived from 4.4BSD-Lite)
have seen increasing use and development.
is a freely available
Unix-like computer operating system descended from Berkeley Software
Distribution (BSD), a Unix derivative created at the University of California,
Berkeley. It was forked from NetBSD, the oldest of the three most popular
BSD-based operating systems still active today (the third being FreeBSD), by
project leader Theo de Raadt in 1995, and is widely known for its developers'
insistence on open source and documentation, uncompromising position on software
licensing, and focus on security and code correctness. The project is
coordinated from de Raadt's home in Calgary, Alberta, Canada. Its logo and
mascot is Puffy, a pufferfish.
OpenBSD includes a number of security features absent or optional in other
operating systems and has a tradition of developers auditing the source code for
software bugs and security problems. The project maintains strict policies on
licensing and prefers the open source BSD licence and its variants—in the past
this has led to a comprehensive licence audit and moves to remove or replace
code under licences found less acceptable.
In common with most other BSD-based operating systems, the OpenBSD kernel and
userland programs, such as the shell and common tools like cat and ps, are
developed together in a single source repository. Third-party software is
available as binary packages or may be built from source using the ports
OpenBSD currently runs on 16 different hardware platforms, including the DEC
Alpha, Intel i386, Hewlett-Packard PA-RISC, AMD AMD64 and Motorola 68000
processors, Apple's PowerPC machines, Sun SPARC and SPARC64-based computers, the
VAX and the Sharp Zaurus.
FreeBSD is a Unix-like free operating system descended from AT&T UNIX via the
Berkeley Software Distribution (BSD) branch through the 386BSD and 4.4BSD
operating systems. It runs on processors compatible with the Intel x86 family,
as well as on the DEC Alpha, the UltraSPARC processors by Sun Microsystems, the
Itanium (IA-64), AMD64 and PowerPC processors. It also runs on the PC-98
architecture. Support for the ARM and MIPS architectures is currently in
is developed as a complete operating system. The kernel, device
drivers and all of the userland utilities, such as the shell, are held in the
same source code revision tracking tree (CVS). This is in contrast to Linux, a
similar but better-known operating system, in which the kernel is developed by
one set of developers; userland utilities and applications by others, such as
the GNU project; and all are packaged together by other groups and published as
As an operating system, FreeBSD is generally regarded as quite reliable and
robust, and of the operating systems that accurately report uptime remotely ,
FreeBSD is the most common free operating system listed in Netcraft's list 
of the 50 web servers with the longest uptime (uptime on some operating systems
such as some versions of Linux can't be calculated). A long uptime also
indicates that no kernel updates have been deemed necessary, as installing a new
kernel requires a reboot and resets the uptime counter of the system.