MIT License
Encyclopedia
The MIT License is a free software license originating at the Massachusetts Institute of Technology
(MIT). It is a permissive
license, meaning that it permits reuse within proprietary software
provided all copies of the licensed software include a copy of the MIT License terms. Such proprietary software
retains its proprietary nature even though it incorporates software under the MIT License.
The license is also GPL-compatible, meaning that the GPL permits combination and redistribution with software that uses the MIT License.
and thus consider the names "Expat license" (used for the Expat
) and the "X11 license" (also called "MIT/X Consortium License"; used for the X Window System
by the MIT X Consortium) to be more accurate. The "MIT License" often used and published on the official site of Open Source Initiative
is the same as the Expat license.
Comparing to the Expat license, X11 license and the "MIT License" used for ncurses
by the Free Software Foundation in 1998 adds this clause:
The XFree86 Project uses a modified MIT License for XFree86
version 4.4 onward. The license includes a clause that requires attribution in software documentation, like the original 4-clause BSD license. The Free Software Foundation
contends that this addition is incompatible with the version 2 of the GPL, but compatible with version 3:
Software packages
that use one of the versions of the MIT License include Expat, PuTTY
, the Mono development platform
class libraries, Ruby on Rails
, Lua (from version 5.0 onwards), and the X Window System, for which the license was written.
The original BSD license also includes a clause requiring all advertising of the software to display a notice crediting its authors. This "advertising clause" (since disavowed by UC Berkeley) is present in the modified MIT License used by XFree86
.
The MIT License states more explicitly 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 used by FreeBSD
(and preferred for NetBSD
) is essentially identical to the MIT License, as it contains neither an advertising clause, nor a prohibition on promotional use of the copyright holder's name.
Also similar in terms is the ISC license, which has a simpler language.
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.
Massachusetts Institute of Technology
The Massachusetts Institute of Technology is a private research university located in Cambridge, Massachusetts. MIT has five schools and one college, containing a total of 32 academic departments, with a strong emphasis on scientific and technological education and research.Founded in 1861 in...
(MIT). It is a permissive
Permissive free software licence
A permissive free software licence is a class of free software licence with minimal requirements about how the software can be redistributed. This is in contrast to copyleft licences, which have reciprocity / share-alike requirements. Both sets of free software licences offer the same freedoms in...
license, meaning that it permits reuse within proprietary software
Proprietary software
Proprietary software is computer software licensed under exclusive legal right of the copyright holder. The licensee is given the right to use the software under certain conditions, while restricted from other uses, such as modification, further distribution, or reverse engineering.Complementary...
provided all copies of the licensed software include a copy of the MIT License terms. Such proprietary software
Proprietary software
Proprietary software is computer software licensed under exclusive legal right of the copyright holder. The licensee is given the right to use the software under certain conditions, while restricted from other uses, such as modification, further distribution, or reverse engineering.Complementary...
retains its proprietary nature even though it incorporates software under the MIT License.
The license is also GPL-compatible, meaning that the GPL permits combination and redistribution with software that uses the MIT License.
Various versions
Since MIT has used many licenses for software, "MIT License" is viewed as ambiguous by the FSFFree Software Foundation
The Free Software Foundation is a non-profit corporation founded by Richard Stallman on 4 October 1985 to support the free software movement, a copyleft-based movement which aims to promote the universal freedom to create, distribute and modify computer software...
and thus consider the names "Expat license" (used for the Expat
Expat (XML)
In computing, Expat is a stream-oriented XML 1.0 parser library, written in C. As one of the first available open-source XML parsers, Expat has found a place in many open-source projects. Such projects include the Apache HTTP Server, Mozilla, Perl, Python and PHP...
) and the "X11 license" (also called "MIT/X Consortium License"; used for the X Window System
X Window System
The X window system is a computer software system and network protocol that provides a basis for graphical user interfaces and rich input device capability for networked computers...
by the MIT X Consortium) to be more accurate. The "MIT License" often used and published on the official site of Open Source Initiative
Open Source Initiative
The Open Source Initiative is an organization dedicated to promoting open source software.The organization was founded in February 1998, by Bruce Perens and Eric S. Raymond, prompted by Netscape Communications Corporation publishing the source code for its flagship Netscape Communicator product...
is the same as the Expat license.
Comparing to the Expat license, X11 license and the "MIT License" used for ncurses
Ncurses
ncurses is a programming library that provides an API which allows the programmer to write text user interfaces in a terminal-independent manner. It is a toolkit for developing "GUI-like" application software that runs under a terminal emulator...
by the Free Software Foundation in 1998 adds this clause:
The XFree86 Project uses a modified MIT License for XFree86
XFree86
XFree86 is an implementation of the X Window System. It was originally written for Unix-like operating systems on IBM PC compatibles and is now available for many other operating systems and platforms. It is free and open source software under the XFree86 License version 1.1. It is developed by the...
version 4.4 onward. The license includes a clause that requires attribution in software documentation, like the original 4-clause BSD license. The Free Software Foundation
Free Software Foundation
The Free Software Foundation is a non-profit corporation founded by Richard Stallman on 4 October 1985 to support the free software movement, a copyleft-based movement which aims to promote the universal freedom to create, distribute and modify computer software...
contends that this addition is incompatible with the version 2 of the GPL, but compatible with version 3:
Software packages
Computer software
Computer software, or just software, is a collection of computer programs and related data that provide the instructions for telling a computer what to do and how to do it....
that use one of the versions of the MIT License include Expat, PuTTY
PuTTY
PuTTY is a free and open source terminal emulator application which can act as a client for the SSH, Telnet, rlogin, and raw TCP computing protocols and as a serial console client...
, the Mono development platform
Mono (software)
Mono, pronounced , is a free and open source project led by Xamarin to create an Ecma standard compliant .NET-compatible set of tools including, among others, a C# compiler and a Common Language Runtime....
class libraries, Ruby on Rails
Ruby on Rails
Ruby on Rails, often shortened to Rails or RoR, is an open source web application framework for the Ruby programming language.-History:...
, Lua (from version 5.0 onwards), and the X Window System, for which the license was written.
License terms
A common form of the MIT license (the same version as the Expat license, not identical with the X sources) is defined as follows:
Copyright (C)by
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.
Comparison to other licenses
The MIT License is similar to the 3-clause "modified" 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, as noted above.The original BSD license also includes a clause requiring all advertising of the software to display a notice crediting its authors. This "advertising clause" (since disavowed by UC Berkeley) is present in the modified MIT License used by XFree86
XFree86
XFree86 is an implementation of the X Window System. It was originally written for Unix-like operating systems on IBM PC compatibles and is now available for many other operating systems and platforms. It is free and open source software under the XFree86 License version 1.1. It is developed by the...
.
The MIT License states more explicitly the rights given to the end-user
End-user
Economics and commerce define an end user as the person who uses a product. The end user or consumer may differ from the person who purchases the product...
, including the right to use, copy, modify, merge, publish, distribute, sublicense, and/or sell the software.
A 2-clause BSD-style license used by FreeBSD
FreeBSD
FreeBSD is a free Unix-like operating system descended from AT&T UNIX via BSD UNIX. Although for legal reasons FreeBSD cannot be called “UNIX”, as the direct descendant of BSD UNIX , FreeBSD’s internals and system APIs are UNIX-compliant...
(and preferred for NetBSD
NetBSD
NetBSD is a freely available open source version of the Berkeley Software Distribution Unix operating system. It was the second open source BSD descendant to be formally released, after 386BSD, and continues to be actively developed. The NetBSD project is primarily focused on high quality design,...
) is essentially identical to the MIT License, as it contains neither an advertising clause, nor a prohibition on promotional use of the copyright holder's name.
Also similar in terms is the ISC license, which has a simpler language.
The University of Illinois/NCSA Open Source License
University of Illinois/NCSA Open Source License
The University of Illinois/NCSA Open Source License is a permissive free software licence, based on the MIT/X11 and BSD licenses. By combining parts of these two licenses, it attempts to be clearer and more concise than either....
combines text from both the MIT and BSD licenses; the license grant and disclaimer are taken from the MIT License.
External links
- The MIT License template (Open Source Initiative official site)
- Expat license
- X11 license
- XFree86 License