MIT License
The MIT License, also called the X License or the X11 License, originated at the Massachusetts Institute of Technology, is a license for the use of certain types of computer software. It is permissive free software licence, which means it allows reuse as proprietary software.
Software packages that use the MIT License include Expat, PuTTY, Mono development platform class libraries, Ruby on Rails, Lua 5.0 onwards and perhaps most famously the X Window System.
The license is short and simple. Its text follows:
Copyright (c) <year> <copyright holders> Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
Because the MIT License is not copyrighted, the license can be modified to suit particular needs. For example, the Free Software Foundation uses a license identical to the MIT License for its ncurses library.
Often the license has the following text as well, which is not actually needed, but present to remind people of their legal obligations:
- Except as contained in this notice, the name(s) of the above copyright holders shall not be used in advertising or otherwise to promote the sale, use or other dealings in this Software without prior written authorization.
The following clause is always found in the license:
- The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
This clause is generally only a restating of protections provided by applicable copyright law, including that of the United States.
Some software packages dual-license their products under the MIT License, including older versions of the cURL library, which allowed you to choose either the Mozilla Public License or the MIT License.
According to the Free Software Foundation, the MIT License is more accurately called the X11 license, since MIT has used many licenses for software and the license was first drafted for the X Window System.[1] The Open Source Initiative refers to it as the MIT License, as do most others.
Comparison to other licenses
The MIT License is similar to the 3-clause BSD license, except that the BSD license contains a notice prohibiting the use of the name of the copyright holder in promotion. This is sometimes present in versions of the MIT License.[citation needed] However, the 3-clause BSD license also requires that the copyright notice be present in accompanying documentation.
The 4-clause BSD license also includes a clause requiring all advertising of the software to display a notice (explicitly disavowed by UC Berkeley, but not necessarily disavowed by other copyright holders). The MIT License has never had this clause. The MIT License, however, more explicitly states the rights given to the end-user, including the right to use, copy, modify, merge, publish, distribute, sublicense, and/or sell the software.
A 2-clause BSD-style license, found in software such as Apple’s WebCore (though most of WebCore is under the LGPL) is, practically, the same as the MIT License, as it does not contain the "promotion" clause.
The University of Illinois/NCSA Open Source License combines text from both the MIT and BSD licenses; the license grant and disclaimer are taken from the MIT License.
