BSD licenses represent a family of permissive free software licenses. The original was used for the
Berkeley Software DistributionBerkeley Software Distribution is the UNIX operating system derivative developed and distributed by the Computer Systems Research Group of the University of California, Berkeley, from 1977 to 1995....
(BSD), a
Unix-likeA Unix-like operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification....
operating system after which the license is named. The original owners of BSD were the
Regents of the University of CaliforniaThe Regents of the University of California make up the governing board of the University of California. The Board has 26 full members:* The majority are appointed by the Governor of California for 12-year terms....
because BSD was first written at the
University of California, BerkeleyThe University of California, Berkeley is a public research university located in Berkeley, California, United States. The oldest of the ten major campuses affiliated with the University of California, Berkeley offers some 300 undergraduate and graduate degree programs in a wide range of disciplines...
. The first version of the license was revised, and the resulting licenses are more properly called modified BSD licenses. Permissive licenses, sometimes with important differences pertaining to
license compatibilityLicense compatibility refers to the problem with licenses of software packages which can contain contradictory requirements, rendering it impossible to combine source code from such packages in order to create new software packages....
, are referred to as "BSD-style licenses".
BSD licenses represent a family of permissive free software licenses. The original was used for the
Berkeley Software DistributionBerkeley Software Distribution is the UNIX operating system derivative developed and distributed by the Computer Systems Research Group of the University of California, Berkeley, from 1977 to 1995....
(BSD), a
Unix-likeA Unix-like operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification....
operating system after which the license is named. The original owners of BSD were the
Regents of the University of CaliforniaThe Regents of the University of California make up the governing board of the University of California. The Board has 26 full members:* The majority are appointed by the Governor of California for 12-year terms....
because BSD was first written at the
University of California, BerkeleyThe University of California, Berkeley is a public research university located in Berkeley, California, United States. The oldest of the ten major campuses affiliated with the University of California, Berkeley offers some 300 undergraduate and graduate degree programs in a wide range of disciplines...
. The first version of the license was revised, and the resulting licenses are more properly called modified BSD licenses. Permissive licenses, sometimes with important differences pertaining to
license compatibilityLicense compatibility refers to the problem with licenses of software packages which can contain contradictory requirements, rendering it impossible to combine source code from such packages in order to create new software packages....
, are referred to as "BSD-style licenses". Several BSD-like licenses, including the New BSD license, have been
vettedVetting is a process of examination and evaluation, generally referring to performing a background check on someone before offering him or her employment...
by the
Open Source InitiativeThe Open Source Initiative is an organization dedicated to promoting open source software.The organization was founded in February 1998, by Bruce Perens and Eric S. Raymond, prompted by Netscape Communications Corporation publishing the source code for its flagship Netscape Communicator product...
as meeting their definition of
open sourceOpen source is an approach to the design, development, and distribution of software, offering practical accessibility to a software's source code. Some consider open source as one of various possible design approaches, while others consider it a critical strategic element of their operations...
.
The licenses have few restrictions compared to other free software licenses such as the
GNU General Public LicenseThe GNU General Public License is a widely used free software license, originally written by Richard Stallman for the GNU project....
or even the default restrictions provided by
copyrightCopyright is a form of intellectual property that gives the author of an original work exclusive right for a certain time period in relation to that work, including its publication, distribution and adaptation, after which time the work is said to enter the public domain...
, putting it relatively closer to the
public domainThe public domain is a range of abstract materials—commonly referred to as intellectual property—which are not owned or controlled by anyone. The term indicates that these materials are therefore "public property", and available for anyone to use for any purpose...
.
Terms
The typical BSD license contains 3 major clauses, allowing unlimited redistribution for any purpose as long as its copyright notices and the license's disclaimers of warranty are maintained. The license also contains a clause restricting use of the names of contributors for endorsement of a derived work without specific permission.
Copyright (c) ,
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* 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.
* Neither the name of the 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 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 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.
UC Berkeley advertising clause
Older versions of the BSD license contained an additional clause, known as the "advertising clause", that eventually became controversial. It required authors of all works deriving from a BSD-licensed work to include an acknowledgment of the original source. This was clause number 3 in the original license text:
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.
This clause was objected to on the grounds that as people changed the
license to reflect their name or organization it led to escalating advertising
requirements when programs were combined together in a software
distribution—every occurrence of the license with a different name
required a separate acknowledgment— the
Free Software FoundationThe Free Software Foundation is a non-profit corporation founded by Richard Stallman on 4 October 1985 to support the free software movement, a copyleft-based movement which aims to promote the universal freedom to distribute and modify computer software...
has
cited the requirement for 75 such acknowledgments when advertising a 1997
version of
NetBSDNetBSD is a freely redistributable, open source version of the Unix-derivative Berkeley Software Distribution computer operating system. It was the second open source BSD descendant to be formally released, after 386BSD, and continues to be actively developed...
.
In addition, the clause presented a legal problem for those wishing to publish
BSD-licensed software which relies upon separate programs using the
more-restrictive
GPLThe GNU General Public License is a widely used free software license, originally written by Richard Stallman for the GNU project....
: the advertising clause is
incompatibleLicense compatibility refers to the problem with licenses of software packages which can contain contradictory requirements, rendering it impossible to combine source code from such packages in order to create new software packages....
with the GPL, which does not allow the
addition of restrictions beyond those it already imposes.
The advertising clause was removed from the official BSD license text on
July 22, 1999 by William Hoskins, the director of the office of
technology licensing for Berkeley. Other BSD
distributions removed the clause, but many similar clauses remain in
BSD-derived code from other sources.
The original license is now sometimes called "BSD-old" or "4-clause BSD",
while the current revision of the BSD license is sometimes referred to by
names including "BSD-new", "revised BSD", or "3-clause BSD".
Proprietary software licenses compatibility
The BSD License allows proprietary use, and for the software released under the license to be incorporated into proprietary products. Works based on the material may be released under a proprietary license or as closed source software. This is the reason for widespread use of the BSD code in proprietary products, ranging from
Juniper NetworksJuniper Networks, Inc.
is an information technology and computer networking products multinational company, founded in 1996. It is headquartered in Sunnyvale, California, USA. The company designs and sells Internet Protocol network products and services...
routers to
Mac OS XMac OS X is a line of computer operating systems developed, marketed, and sold by Apple Inc., and since 2002 has been included with all new Macintosh computer systems...
.
It is possible for something to be distributed with the BSD License and some other license to apply as well. This was in fact the case with very early versions of BSD itself, which included proprietary material from
AT&TAT&T Inc. is the largest provider of local, long distance telephone services in the United States, and also serves digital subscriber line Internet access. AT&T is the second largest provider of wireless service in the United States, with over 77 million wireless customers, and more than 150...
.
BSD-style licenses
Several free or open source licenses that derive from or are similar to the BSD license are widely used:
- NetBSD
NetBSD is a freely redistributable, open source version of the Unix-derivative Berkeley Software Distribution computer operating system. It was the second open source BSD descendant to be formally released, after 386BSD, and continues to be actively developed...
switched from a 4-clause to a 2-clause BSD-like license on June 20, 2008; it removes the third (endorsement/promotion) clause.
- A 2-clause BSD-like license also exists which deletes the third clause, prohibiting use of the copyright
Copyright is a form of intellectual property that gives the author of an original work exclusive right for a certain time period in relation to that work, including its publication, distribution and adaptation, after which time the work is said to enter the public domain...
holder's name for endorsement purposes. Removal of that clause makes the license functionally equivalent to the MIT LicenseThe MIT License is a free software license originating at the Massachusetts Institute of Technology , used by the MIT X Consortium.It is a permissive license, meaning that it permits reuse within proprietary software on the condition that the license is distributed with that software...
. This is the only BSD-style license permitted for certain libraries included in KDEKDE is a free software project based around its flagship product, a desktop environment mainly for Unix-like systems. The goal of the project is to provide basic desktop functions and applications for daily needs as well as tools and documentation for developers to write stand-alone applications...
.
- FreeBSD
FreeBSD is a free Unix-like operating system descended from AT&T UNIX via the Berkeley Software Distribution . It has been characterized as "the unknown giant among free operating systems". It is not a clone of UNIX, but works like UNIX, with UNIX-compliant internals and system APIs. FreeBSD is...
also uses a 2-clause license with an additional statement at the end that the views of contributors are not the official views of the FreeBSD Project.
- FreeBSD
FreeBSD is a free Unix-like operating system descended from AT&T UNIX via the Berkeley Software Distribution . It has been characterized as "the unknown giant among free operating systems". It is not a clone of UNIX, but works like UNIX, with UNIX-compliant internals and system APIs. FreeBSD is...
also provides the FreeBSD Documentation LicenseThe FreeBSD Documentation License is the license that covers the documentation for the FreeBSD operating system. Based on this license, the BSD Documentation License was created to contain terms more generic to most projects as well as reintroducing the 3rd clause that restricts the use of...
, a license similar to the subsequent BSD Documentation License that contains terms specific to documentation.
- OpenBSD
OpenBSD is a Unix-like computer operating system descended from Berkeley Software Distribution , a Unix derivative developed at the University of California, Berkeley. It was forked from NetBSD by project leader Theo de Raadt in late 1995...
uses a license modeled after the ISC license, "equivalent to a two-term BSD copyright with language removed that is made unnecessary by the Berne convention."
- The MIT license
The MIT License is a free software license originating at the Massachusetts Institute of Technology , used by the MIT X Consortium.It is a permissive license, meaning that it permits reuse within proprietary software on the condition that the license is distributed with that software...
is similar to the BSD license.
- The University of Illinois/NCSA Open Source License
The University of Illinois/NCSA Open Source License is a permissive free software licence, based on the MIT/X11 and BSD licenses. By combining parts of these two licenses, it attempts to be clearer and more concise than either....
combines text from both the MIT and BSD licenses, and is equivalent to the 3-clause BSD license.
- The Xiph.Org Foundation
Xiph.Org Foundation is a non-profit organizationthat produces free multimedia formats and software tools. It focuses on the Ogg family of formats, the most successful of which has been Vorbis, an open and patent-free audio format and codec designed to compete with the patented MP3 and AAC...
uses the 3-clause license for the binary libraries of their different projects without significant differences from the New BSD license.
- Microsoft
Microsoft Corporation is a multinational computer technology corporation that develops, manufactures, licenses, and supports a wide range of software products for computing devices...
's Public License is "much like a BSD-style license, except that it prohibits re-licensing if the code is distributed in source code form."
See also
- Permissive and copyleft licenses
A free software licence is a software licence which grants recipients rights to modify and redistribute the software which would otherwise be prohibited by copyright law...
External links