According to http://www.opensource.org the following are the most popular licenses used by open source software.
The analytical terms and conditions of the license can be found in:
http://www.apache.org/licenses/
http://www.opensource.org/licenses/apache2.0.php
One unintended upshot of the creation of the Apache License v2 is that it became incompatible with the GPL v2. The restriction in v2 that terminates the grant of rights if the licensee sues over patent infringement is seen by the Free Software Foundation as a restriction that is not present in the GPL v2. However, with the release of the GPL v3, this incompatibility is no longer insurmountable. The GPL v3 allows for the addition of a patent retaliation clause whose effect is to allow code from a GPL v3-licensed project to be combined with code from an Apache 2-licensed project.[www.oss-watch.ac.uk/resources/apache2.xml]
Useful links:
http://en.wikipedia.org/wiki/Apache_License
http://db.apache.org/derby/license.html
The license prevented what were then the two main ways that software distributors restricted the freedoms that define free software. The first problem was that distributors may publish binary files only – executable, but not readable or modifiable by humans. To prevent this, GPLv1 said that any vendor distributing binaries must also make the human readable source code available under the same licensing terms.
The second problem was the distributors might add additional restrictions, either by adding restrictions to the license, or by combining the software with other software which had other restrictions on its distribution. If this was done, then the union of the two sets of restrictions would apply to the combined work, thus unacceptable restrictions could be added. To prevent this, GPLv1 said that modified versions, as a whole, had to be distributed under the terms in GPLv1. Therefore, software distributed under the terms of GPLv1 could be combined with software under more permissive terms, as this would not change the terms under which the whole could be distributed, but software distributed under GPLv1 could not be combined with software distributed under a more restrictive license, as this would conflict with the requirement that the whole be distributable under the terms of GPLv1. [en.wikipedia.org/wiki/GNU_General_Public_License#Version_1]
The second version was published in 1991.The analytical terms and conditions of this license are in http://www.gnu.org/licenses/old-licenses/gpl-2.0.html.
According to Richard Stallman, the major change in GPLv2 was the "Liberty or Death" clause, as he calls it - Section 7. This section says that if someone has restrictions imposed that prevent him or her from distributing GPL-covered software in a way that respects other users' freedom (for example, if a legal ruling states that he or she can only distribute the software in binary form), he or she cannot distribute it at all.
By 1990, it was becoming apparent that a less restrictive license would be strategically useful for some software libraries; when version 2 of the GPL (GPLv2) was released in June 1991, therefore, a second license - the Library General Public License (LGPL) was introduced at the same time and numbered with version 2 to show that both were complementary. The version numbers diverged in 1999 when version 2.1 of the LGPL was released, which renamed it the GNU Lesser General Public License to reflect its place in the GNU philosophy. [en.wikipedia.org/wiki/GNU_General_Public_License#Version_2]
The third version was published in 2007. The analytical terms and conditions of this license are in http://www.gnu.org/licenses/gpl-3.0.html.
GPLv3 was written by Richard Stallman, with legal counsel from Eben Moglen and Software Freedom Law Centre. According to GPLv3 author, Richard Stallman, the most important changes are in relation to software patents, free software license compatibility, the definition of "source code", and hardware restrictions on software modification ("tivoisation"). Other changes relate to internationalisation, how license violations are handled, and how additional permissions can be granted by the copyright holder.
Other notable changes include allowing authors to add certain additional conditions or requirements to their contributions. One of those new optional requirements, sometimes referred to as the Affero clause, is intended to fulfil a request regarding software as a service; the permitting addition of this requirement makes GPLv3 compatible with the Affero General Public License. [en.wikipedia.org/wiki/GNU_General_Public_License#Version_3]
Useful links:
http://www.gnu.org/licenses/gpl-faq.html
Why upgrade in GPLv3, http://www.gnu.org/licenses/rms-why-gplv3.html
http://creativecommons.org/licenses/GPL/2.0/
http://www.fsf.org/news/gplv3_launched
http://www.law.ed.ac.uk/ahrc/script-ed/vol3-2/guadamuz.asp
The LGPL is intended to apply to libraries and code that is intended to plug into other code. It specifically addresses the problem that the GPL has of "expanding" to include code that just calls GPL-licensed libraries, since the GPL's definition of "derivative work" includes code that simply links with GPL code.
Useful Links:
http://www.flexwiki.com/default.aspx/FlexWiki/LicenseResearch.html
http://en.wikipedia.org/wiki/GNU_Lesser_General_Public_License
http://creativecommons.org/licenses/LGPL/2.1/
http://opensource.franz.com/preamble.html
The MIT license is one of the most liberal open source licenses and is almost identical with BSD License. It originated from Massachusetts Institute of Technology for the X Window System (1984). Alternatively, this license is referenced as X11 license, since MIT has used many licences for software and was first drafted for X Windows System.
The MIT license allows the linkage with proprietary software, which means that it permits reuse and modification within the proprietary software as long as the license is distributed with that software. The MIT License states explicitly the rights given to the end-user, including the right to use, copy, modify, merge, publish, distribute, sublicense, and/or sell the software. Since there is no charge, there is no warranty of any kind.
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. The original BSD license also includes a clause requiring all advertising of the software to display a notice crediting its authors. This "advertising clause" is only present in the modified MIT License used by XFree86. A 2-clause BSD-style license, found in software such as Apple Inc.'s WebKit (though most of WebKit is under the LGPL) is essentially identical to the MIT License, as it does not contain an advertising clause.
Useful Links:
http://en.wikipedia.org/wiki/MIT_License
http://www.opensource.org/licenses/mit-license.php
http://el.wikipedia.org/wiki/X_Window_System
http://www.linfo.org/mitlicense.html
Useful Links:
http://www.mozilla.org/MPL/MPL-1.1.html
http://en.wikipedia.org/wiki/Mozilla_Public_License
The Eclipse Public License is written for use by the Eclipse Foundation. The EPL is a derivative from CPL (Common Public License). The EPL defines the limitations of “Contributions” to the original Program. As “Contributions” it refers to changes or additions made to the Program.
The contributor can make, use, sell, offer to sell, import and transfer the contribution and release it under its own license, as long as it states that the provisions mentioned in the license are offered by the contributor alone and not by any other party.
Useful Links:
http://en.wikipedia.org/wiki/Eclipse_Public_License
http://www.eclipse.org/legal/epl-v10.html
http://www.eclipse.org/legal/eplfaq.php
The PHP license (latest version 3.01) is used by PHP scripting language, mainly used in web developing. In general, the PHP license allows the user to use, distribute and modify PHP in any way, whether it’s for commercial or non commercial use. The only real restriction is that it must be made clear to the user that the distributed software contains PHP.
More specifically, the license must be contained in the software’s documentation (including the PHP license copyright statement) and also the product must retain the acknowledgement “This product includes PHP, freely available from ". Also products derived from PHP cannot contain the term “PHP” in their title. They can though indicate that the product works in conjunction with PHP by applying the term “for PHP” at the end of the product title.
Useful Links:
http://www.php.net/license/3_01.txt
http://en.wikipedia.org/wiki/PHP_License
Useful Links:
http://www.python.org/psf/license/
http://en.wikipedia.org/wiki/Python_License
http://swik.net/License:Python-License
The Common Public Attribution License ("CPAL") is a free software license approved by the Open Source Initiative in 2007. Its purpose is to be a general license for software distributed over a network. It is based on the Mozilla Public License, but it adds a controversial attribution term paraphrased below:
[…] the Original Developer may include […] a requirement that each time an Executable and Source Code or a Larger Work is launched or initially run […] a prominent display of the Original Developer's Attribution Information […] must occur on the graphic user interface employed by the end user to access such Covered Code […] [http://en.wikipedia.org/wiki/Common_Public_Attribution_License]
Useful links:
http://www.eu.socialtext.net/open/index.cgi?cpal_faq
http://www.eu.socialtext.net/open/index.cgi?how_to_apply_the_cpal_to_your_product
The analytical terms and conditions of the license can be found in http://www.gnu.org/copyleft/lgpl.html
The GNU Lesser General Public License was written in 1991 (and updated in 1999) by Richard Stallman, with legal advice from Eben Moglen.
The LGPL places copyleft restrictions on the program itself but does not apply these restrictions to other software that merely links with the program. There are, however, certain other restrictions on this software.
The LGPL is primarily used for software libraries, although it is also used by some stand-alone applications, most notably Mozilla and OpenOffice.org. [en.wikipedia.org/wiki/GNU_Lesser_General_Public_License]
The main difference between the GPL and the LGPL is that the latter can be linked to (in the case of a library, 'used by') a non-(L)GPLed program, which may be free software or proprietary software . This non-(L)GPLed program can then be distributed under any chosen terms if it is not a derivative work. If it is a derivative work, then the terms must allow "modification for the customer's own use and reverse engineering for debugging such modifications." Whether a work that uses an LGPL program is a derivative work or not is a legal issue. A standalone executable that dynamically links to a library is generally accepted as not being a derivative work. It would be considered a "work that uses the library" and paragraph 5 of the LGPL applies.
A program that contains no derivative of any portion of the Library, but is designed to work with the Library by being compiled or linked with it, is called a "work that uses the Library". Such a work, in isolation, is not a derivative work of the Library, and therefore falls outside the scope of this License.
Essentially, it must be possible for the software to be linked with a newer version of the LGPL-covered program. The most commonly used method for doing so is to use "a suitable shared library mechanism for linking". Alternatively, a statically linked library is allowed if either source code or linkable object files are provided.
One feature of the LGPL is that one can convert any LGPLed piece of software into a GPLed piece of software (section 3 of the license). This feature is useful for direct reuse of LGPLed code in GPLed libraries and applications, or if one wants to create a version of the code that software companies cannot use in proprietary software products. [en.wikipedia.org/wiki/GNU_Lesser_General_Public_License#Differences_from_the_GPL]
Useful links:
http://www.gnu.org/copyleft/lgpl.html
http://www.opensource.org/licenses/lgpl-license.php
The Reciprocal Public License (RPL) is a software license inspired by the GNU General Public License (GPL) but authored to explicitly remove what some have referred to as the GPL's "privacy loophole"—an aspect of the GPL which allows recipients of GPL'd code to:
1) Make changes to source code which are never released to the open source community (by virtue of not deploying "to a third party"), and
2) Derive financial or other business benefit from that action, violating what some might consider a simple concept of "fairness".
The "R" in RPL stands for "Reciprocal" specifically to call out that this license requires software developers and companies to reciprocate for the benefits they derive from RPL'd software by releasing any extensions or improvements they make regardless of whether those changes deploy internally or to third parties.
Because of its "viral" nature, the RPL is often found in dual-licensing models in which it is paired with more traditional closed-source licenses. This strategy allows software companies who use this model to present customers with a "pay with cash or pay with code" option, ensuring either the growth of the software directly through code contributions or indirectly through cash which can be used to fund further development.
The RPL was written to conform to the requirements of the Open Source Initiative to ensure that it met the goals for an Open Source license, however because of its requirements for reciprocation the RPL holds the unique distinction of being the only software license both approved by the Open Source Initiative and explicitly called out as non-free for matters of substance by the Free Software Foundation (the FSF considers the Artistic License too vague to be definitively free).
Useful links:
http://www.opensource.org/licenses/rpl1.0.php, previous version.
Simple Public License is a plain language implementation of GPL 2.0. It allows the user to use the software for any purpose, whether it is for commercial or non commercial use. If there are any changes made, the date of changes should be mentioned and leave other people’s license terms in place, while the availability under the SimPL license must be conspicuously announced.
Useful Links:
http://www.opensource.org/licenses/simpl-2.0.html
Creative commons has come up with 6 different types of licensing, allowing creators to “mark their work with the freedoms they want it to carry”. They are the following:
Attribution
Allows people to distribute, remix, tweak and build upon someone’s work as long as they credit the original creation. Allows commercial use.
Attribution Share Alike
Same with attribution, with the limitation of any further distributions of the product being licensed under identical terms with the original. Also allows commercial use.
Attribution No Derivatives
Allows redistribution of the product as long as it remains unchanged and there is credit to the original creator. Also allows commercial use.
Attribution Non Commercial Share Alike
Same with attribution, although doesn’t allow commercial use and the final product license can differ from the initial one.
Attribution Non Commercial
This is actually the same with attribution Non Commercial Share Alike, the final product license though must be identical with the original product’s one.
Attribution Non Commercial No Derivatives
Same with attribution no derivatives, with the further restriction of non commercial use.
As anyone can notice, all of these licenses allow redistribution of the original work - whether it’s changed or not, as long as there is credit to the original creator.
Useful Links:
http://creativecommons.org/about/license/
License
|
Proprietary Software linking
|
Distribution of “the Work”
|
Redistributing of the code with changes
|
GNU GPL Compatible
|
Apache License
|
Allowed.
|
Allowed.
|
Allowed (as long as the name “Apache” isn't used in the name of the derivative work)
|
No
|
GPL
|
Not allowed (since the linked software is considered a whole)
|
Not allowed with software whose license is not GNU GPL compatible.
|
Only if the derivative is GNU GPL.
|
Yes
|
LGPL
|
Allowed (since the software that links to the library is not considered a derivative work)
|
Allowed with some restrictions: You have to provide source code of the distributed LGPL library with (if any) modifications, changes to the LGPL library should be allowed to third parties and if BC your app/lib should still work with the modified LGPL lib/app.
|
Only if the derivative is GNU LGPL or GNU GPL.
|
Yes
|
MIT
|
Allowed
|
Allowed
|
Allowed.
|
Yes
|
MPL
|
Allowed
|
Allowed
|
Only under MPL.
|
No/Yes
|
Python
|
Allowed
|
Allowed
|
Allowed, assuming the package includes a list of changes to the original Python and copyright notices on all files.
|
Yes
|
CPAL (MPL based)
|
See MPL
|
See MPL
|
See MPL
|
See MPL
|
RPL
|
Allowed
|
Allowed
|
Allowed
|
Yes
|
SimPL (GPL based)
|
See GPL
|
See GPL
|
See GPL
|
See GPL
|
EPL
|
Allowed
|
Allowed
|
Allowed
|
No
|
CC Attribution
|
Allowed
|
Allowed
|
Allowed
|
No
|
CC Attr ND
|
Allowed
|
Allowed (as long as there is credit to the creator)
|
Not Allowed
|
No
|
CC Attr NC SA
|
Allowed
|
Allowed (for non commercial use)
|
Allowed
|
No
|
CC Attr NC
|
Allowed
|
Allowed (under the same license with the original and for non commercial use)
|
Allowed
|
No
|
CC Attr ND NC
|
Allowed
|
Allowed (for non commercial use)
|
Not Allowed
|
No
|
CC Attr SA
|
Allowed
|
Allowed
|
Allowed
|
No
|
PHP License
|
Allowed
|
Allowed
|
Allowed (as long as "PHP" is not contained in the name of the derivative work)
|
No
|
Useful Links:
http://developer.kde.org/documentation/licensing/licenses_summary.html