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What is the BSD License?

This page shares some examples of a BSD licenses, some details about the BSD license philosophy, and a few links to more information about the BSD license.

Some interesting quotes and comments
BSD license examples
Examples of usage of BSD-licensed code
Links to other BSD licensing info

The only requirements of the BSD license are preservation of copyright and a standard disclaimer of liability. Due to its minimal license, BSD software can be freely modified and used in proprietary or commercial software.

Many (usually older) BSD licenses include a clause that said advertising materials must display acknowledgement. In 1999, the Office of Technology Licensing at University of California at Berkeley stated: "Effective immediately, licensees and distributors are no longer required to include the acknowledgement within advertising materials. Accordingly, the foregoing paragraph of those BSD Unix files containing it is hereby deleted in its entirety." (This applies to UCB-licensed materials.)

Also some BSD licenses include a clause that restricts the use of the project (or contributors) for endorsing or promoting by-products.

Some interesting quotes and comments

The NetBSD Goals page says:

In general, developers pattern their license terms after what's known as the "Berkeley license."
Berkeley-style licenses ... allow people to copy and modify the software, so long as we get name recognition and our names aren't used without our permissions.
[T]he GNU General Public License ... is very different from the Berkeley license.

The FreeBSD FAQ says:

We believe that our first and foremost ``mission'' is to provide code to any and all comers, and for whatever purpose, so that the code gets the widest possible use and provides the widest possible benefit.
[W]e ... endeavor to replace such [GPL] software with submissions under the more relaxed BSD copyright whenever possible.

And the OpenBSD Policy webpage says:

Copyright law is complex, OpenBSD policy is simple - OpenBSD strives to maintain the spirit of the original Berkeley Unix copyrights.
... software bound by the GPL terms can not be included in the kernel or "runtime" of OpenBSD, though software subject to GPL terms may be included as development tools or as part of the system that are "optional" as long as such use does not result in OpenBSD as a whole becoming subject to the GPL terms.

Kirk McKusick interview:

... Berkeley had what we called "copycenter," which is "take it down to the copy center and make as many copies as you want." You want to go off and do proprietary things with it? Fine, you can do that. You want to keep it out in the Open Source domain? You're welcome to do that as well.

BSD License examples

From NetBSD's /usr/src/sys/netinet6/ipsec.c:

Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
   notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
   notice, this list of conditions and the following disclaimer in the
   documentation and/or other materials provided with the distribution.
3. Neither the name of the project nor the names of its contributors
   may be used to endorse or promote products derived from this software
   without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
SUCH DAMAGE.

From 4.4BSD-Lite's /usr/src/bin/rm/rm.1 (Apr. 18, 1994):

Copyright (c) 1990, 1993, 1994
    The Regents of the University of California.  All rights reserved.

This code is derived from software contributed to Berkeley by
the Institute of Electrical and Electronics Engineers, Inc.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
   notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
   notice, this list of conditions and the following disclaimer in the
   documentation and/or other materials provided with the distribution.
3. All advertising materials mentioning features or use of this software
   must display the following acknowledgement:
    This product includes software developed by the University of
    California, Berkeley and its contributors.
4. Neither the name of the University nor the names of its contributors
   may be used to endorse or promote products derived from this software
   without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AN
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
SUCH DAMAGE.

From Wietse Venema's DISCLAIMER for tcp wrappers library:

Copyright 1995 by Wietse Venema.  All rights reserved.  Some individual
files may be covered by other copyrights.

This material was originally written and compiled by Wietse Venema at
Eindhoven University of Technology, The Netherlands, in 1990, 1991,
1992, 1993, 1994 and 1995.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that this entire copyright notice
is duplicated in all such copies.

This software is provided "as is" and without any expressed or implied
warranties, including, without limitation, the implied warranties of
merchantibility and fitness for any particular purpose.

Examples of usage of BSD-licensed code

Commercial / Proprietary

Apple Mac OS X
"Beneath the appealing, easy-to-use interface of Mac OS X, you'll find an industrial-strength, UNIX-based foundation, called Darwin ... At its core, Darwin uses BSD." (See Darwin below.)

Open Source

Darwin
"Darwin is a version of the BSD UNIX operating system ... the BSD license is very open, which has made it easy for us to leverage its compelling core technology to enhance the Mac OS. ... Darwin is simply BSD tweaked in ways we think will help Apple deliver the next great version of the Mac OS." (Darwin itself uses the Apple Public Source License.)

Links to BSD licensing information

The BSD License Problem
http://www.gnu.org/philosophy/bsd.html
Some thoughts about BSD from the GNU site.

UCB License Change
ftp://ftp.cs.berkeley.edu/ucb/4bsd/README.Impt.License.Change

BSD vs. GPL and social aspects of free licensing debate
http://www.softpanorama.org/Copyright/License_classification/index.shtml

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