Expat License
| Publisher | Massachusetts Institute of Technology |
|---|---|
| DFSG compatible | Yes |
| FSF approved | Yes |
| OSI approved | Yes |
| GPL compatible | Yes |
| Copyleft | No |
| Linking from code with a different license | Yes |
The MIT License is a permissive free software license originating at the Massachusetts Institute of Technology (MIT). As a permissive license, it puts only very limited restriction on reuse and has, therefore, an excellent license compatibility. The MIT license permits reuse within proprietary software provided that all copies of the licensed software include a copy of the MIT License terms and the copyright notice. The MIT license is also compatible with many copyleft licenses, such as the GNU General Public License (GPL); MIT licensed software can be integrated into GPL software, but not the other way around.
As of 2015[update], it is the most popular software license, ahead of any GPL variant and other Free and open-source software (FOSS) licenses. Notable projects that use one of the versions of the MIT License include Ruby on Rails, Node.js, jQuery, and the X Window System.
A common form of the MIT License (from the OSI's website, which is the same version as the "Expat License", and which is not identical to the license used in the X source code) is defined as follows:
An intermediate form of license used by the X Consortium for X11 used the following wording:
Because MIT has used many licenses for software, the Free Software Foundation considers "MIT License" ambiguous. "MIT License" may refer to the "Expat License" (used for Expat) or to the "X11 License" (also called "MIT/X Consortium License"; used for the X Window System by the MIT X Consortium). The "MIT License" published by the Open Source Initiative is the same as the "Expat License".
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