BSD licenses are a family of permissive software licenses. The original BSD license was created as part of the Berkeley Software Distribution Operating System. The 4 Clause BSD License was first released in 1990.
The BSD license has been modified and revised several times since its initial creation and there are currently 4 different versions of the license in use. In addition to being a specific license. BSD is also used to describe a class of licenses, generally referred to as BSD-like, which are based on one of the BSD license iterations.
The 4 clause license is the original BSD License. The most significant difference between the 4 clause and all subsequent iterations of the BSD license is the inclusion of an "advertising clause" which required acknowledgment of the original source of the code in all advertising materials.
The advertising clause, the third clause below created a conflict with the GNU GPL license because the GPL license does not allow the addition of restrictions beyond those it already imposes. This incompatibility would be addressed in future revisions of both the BSD and GNU GPL licenses.
Copyright (c) <year>, <copyright holder> 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.
All advertising materials mentioning features or use of this software must display the following acknowledgement: This product includes software developed by the <copyright holder>.
Neither the name of the <copyright holder> 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 <COPYRIGHT HOLDER> 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 <COPYRIGHT HOLDER> 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.
The 3 clause BSD License was released by William Hoskins, Director of the Office of Technology Licensing for UC Berkeley in 1999. The 3 clause BSD License (BSD-3) removed the advertising clause. Also referred to as the "Modified BSD License" or "New BSD" is compatible with the GNU GPL and has been vetted by the Open Source Initiative
Copyright <year> <copyright holder>
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT HOLDER 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.
Also in 1999 a even more simplified version of the BSD license was released. The BSD 2 Clause, often known as FreeBSD.
The basic difference between FreeBSD and BSD 3-clause License is that BSDFree omits the non-endorsement clause. The FreeBSD version of the license also adds a further disclaimer about views and opinions expressed in the software. Although this clause seem to not commonly be included. Like thee BSD 3-clause BSDFree is compatible with the GNU GPL.
Copyright (c) <year>, <copyright holder>
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.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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.
The BSD Zero Clause license removed the requirement to include a copyright statement, license text, or disclaimer in the source code, binary code or any form. The removal of these clauses creates a Public Domain equivalent license it is similar to the MIT No Attribution License.
Copyright (C) [year] by [copyright holder] <[email]>
Permission to use, copy, modify, and/or distribute this software for any purpose with or without fee is hereby granted.
THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE
Because there are several different versions of the BSD license, and BSD like licenses it is suggest that you specify exactly which BSD license you are using in your documentation. Especially to avoid confusion between the original BSD-4 Clause and subsequent licenses. As opposed to including more general language like BSD license or BSD like license.
The BSD family of licenses was developed before patenting software was a common practice in the U.S. They therefore do not contain an express patent license. The broad nature of the license in general, is considered by some to encompass an implicit waiver of patent rights. If you are concerned about patent rights, the Apache 2.0 license contains an explicit contributor's patent license.
The BSD Family of licenses are highly compatible the BSD 3 and 2 clause licenses are considered compatible with the Apache 2.0, as well as the MIT License. BSD 3 is compatible with GNU-GPL family of license. The major exception to this is the original BSD 4 Clause license, which isn't GNU-GPL compliant and may cause issues when combined with other licenses.
