BSD license
| Author | Regents of the University of California |
|---|---|
| Publisher | Public Domain |
| Published | 1988 |
| DFSG compatible | Yes |
| FSF approved | Yes |
| OSI approved | No |
| GPL compatible | No |
| Copyleft | No |
| Linking from code with a different license | Yes |
| Author | Regents of the University of California |
|---|---|
| Publisher | Public Domain |
| Published | 1990 |
| DFSG compatible | Yes |
| FSF approved | Yes |
| OSI approved | No |
| GPL compatible | No |
| Copyleft | No |
| Linking from code with a different license | Yes |
| Author | Regents of the University of California |
|---|---|
| Publisher | Public Domain |
| Published | 22 July 1999 |
| DFSG compatible | Yes |
| FSF approved | Yes |
| OSI approved | Yes |
| GPL compatible | Yes |
| Copyleft | No |
| Linking from code with a different license | Yes |
| Author | The FreeBSD Project |
|---|---|
| Publisher | Public Domain |
| Published | April 1999 or earlier |
| DFSG compatible | Yes |
| FSF approved | Yes |
| OSI approved | Yes |
| GPL compatible | Yes |
| Copyleft | No |
| Linking from code with a different license | Yes |
BSD licenses are a family of permissive free software licenses, imposing minimal restrictions on the redistribution of covered software. This is in contrast to copyleft licenses, which have reciprocity share-alike requirements. The original BSD license was used for its namesake, the Berkeley Software Distribution (BSD), a Unix-like operating system. The original version has since been revised and its descendants are more properly termed modified BSD licenses. BSD is both a license and a class of license (generally referred to as BSD-like). The modified BSD license (in wide use today) is very similar to the license originally used for the BSD version of Unix. The BSD license is a simple license that merely requires that all code licensed under the BSD license be licensed under the BSD license if redistributed in source code format. BSD (unlike some other licenses) does not require that source code be distributed at all.
In addition to the original (4-clause) license used for BSD, several derivative licenses have emerged that are also commonly referred to as a "BSD license". Today, the typical BSD license is the 3-clause version, which is revised from the original 4-clause version.
In all BSD licenses as following, <organization> is the organization of the <copyright holder> or just the <copyright holder>, and <year> is the year of the copyright. As published in BSD, <copyright holder> is "Regents of the University of California", and <organization> is "University of California, Berkeley".
Some releases of BSD prior to the adoption of the 4-clause BSD license used a license that is clearly ancestral to the 4-clause BSD license. These releases include 4.3BSD-Tahoe (1988) and Net/1 (1989). Though largely replaced by the 4-clause license, this license can be found in 4.3BSD-Reno, Net/2, and 4.4BSD-Alpha.
The original BSD license contained a clause not found in later licenses, known as the "advertising clause". This clause eventually became controversial, as it required authors of all works deriving from a BSD-licensed work to include an acknowledgment of the original source in all advertising material. This was clause number 3 in the original license text:
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. In arguing against it, Richard Stallman has stated that he counted 75 such acknowledgments in a 1997 version of NetBSD. In addition, the clause presented a legal problem for those wishing to publish BSD-licensed software which relies upon separate programs using the GNU GPL: the advertising clause is incompatible with the GPL, which does not allow the addition of restrictions beyond those it already imposes; because of this, the GPL's publisher, the Free Software Foundation, recommends developers not use the license, though it states there is no reason not to use software already using it.
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