Public-domain equivalent licenses offer many of the same freedoms as releasing a work to the public domain. The permissive licenses used in free software are well known examples, and include the MIT license and the BSD license. In contrast, Copyleft free licenses like the GNU General Public License require copies and derivatives of the source code to be made available on the same terms as the original license. The public domain comprises the body of all creative works and other knowledge—writing, artwork, music, science, inventions, and others—in which no person or organization has any proprietary interest. ... Free software, as defined by the Free Software Foundation, is software which can be used, copied, studied, modified and redistributed without restriction. ... The MIT License, originated at the Massachusetts Institute of Technology, is a license for the use of certain types of computer software. ... The BSD license is a permissive license and is one of the most widely used licenses for free software. ... To meet Wikipedias quality standards, this article may require cleanup. ... The GNU logo The GNU General Public License (GNU GPL or simply GPL) is the most popular free software license, originally written by Richard Stallman for the GNU project. ...

Computer Associates Int'l v. Altai used the term "public domain" to refer to works that have become widely shared and distributed under permission, rather than work that was deliberately put into the public domain. The earliest licenses, like the license for the X Window System released by MIT in 1985, did not pretend to retain rights of any significance. Computer Associates International, Inc. ... KDE 3. ... The Massachusetts Institute of Technology, or MIT, is a research and educational institution located in the city of Cambridge, Massachusetts, USA. MIT is a world leader in science and technology, as well as in many other fields, including management, economics, linguistics, political science, and philosophy. ... This article is about the year. ...

A public-domain equivalent license, if effective, is not actually equivalent to releasing a work into the public domain. But because the MIT and BSD licenses essentially retain no rights, the purported copyright holders would not be losing rights if a court held that the works were actually in the public domain. The public domain comprises the body of all creative works and other knowledge—writing, artwork, music, science, inventions, and others—in which no person or organization has any proprietary interest. ...