BSD licenses

BSD licenses are a low restriction type of license for open source software that does not put requirements on redistribution.

As a low restriction and requirement license type, Berkeley Source Distribution (BSD) licenses are used for the distribution of many freeware, shareware and open source software. BSD licenses are much like the license that accompanied the original BSD. The original BSD Unix license was first written in 1969. There are 4 main clauses of the classic BSD license:

1. The BSD UNIX license states one may copy, modify and redistribute the code so long as one retains a copy of the original copyright statement.
2. The copyright statements must include a clear statement of two restrictions for use of the distributed software.
3. A disclaimer for limitations of liability that include not claiming authorship of the code where the code was not written by the user and not suing the author of the program for unexpected or undesirable functionality.
4. The stipulation that one doesn’t use the name of the software or its authors to advertise or promote work derived from modification of the distributed code without prior written consent.

Similarly, other BSD licenses can have these clauses but may not include them all. As a base, the first two clauses are a part of any BSD license. There are two, three and four clause BSD licenses.

One of the main differences between a GNU General Public License (GNU GPL or simply GPL), the most common type of license for free software, and a BSD license is that GPL are copyleft, meaning any derivative code produced from the original free open source code must remain free. BSD licenses may allow for derivative works to become paid software.