Share-alike is a copyright licensing term, originally used by the

Creative Commons Creative Commons (CC) is an American non-profit organization and international network devoted to educational access and expanding the range of creative works available for others to build upon legally and to share. The organization has release ...

project, to describe works or licenses that require copies or adaptations of the work to be released under the same or similar license as the original.

Copyleft Copyleft is the legal technique of granting certain freedoms over copies of copyrighted works with the requirement that the same rights be preserved in derivative works. In this sense, ''freedoms'' refers to the use of the work for any purpose, ...

licenses are

free content Free content, libre content, libre information, or free information is any kind of creative work, such as a work of art, a book, a software program, or any other creative content for which there are very minimal copyright and other legal limi ...

free software Free software, libre software, libreware sometimes known as freedom-respecting software is computer software distributed open-source license, under terms that allow users to run the software for any purpose as well as to study, change, distribut ...

licenses with a share-alike condition. Two currently-supported Creative Commons licenses have the ShareAlike condition: Creative Commons Attribution-ShareAlike (a

copyleft Copyleft is the legal technique of granting certain freedoms over copies of copyrighted works with the requirement that the same rights be preserved in derivative works. In this sense, ''freedoms'' refers to the use of the work for any purpose, ...

license) and Creative Commons Attribution-NonCommercial-ShareAlike (a proprietary license). The term has also been used outside copyright law to refer to a similar plan for

patent licensing A license (American English) or licence ( Commonwealth English) is an official permission or permit to do, use, or own something (as well as the document of that permission or permit). A license is granted by a party (licensor) to another par ...

Copyleft

Copyleft or libre share-alike licenses are the largest subcategory of share-alike licenses. They include both

licenses like Creative Commons Attribution-ShareAlike and

licenses like the

GNU General Public License The GNU General Public Licenses (GNU GPL or simply GPL) are a series of widely used free software licenses, or ''copyleft'' licenses, that guarantee end users the freedom to run, study, share, or modify the software. The GPL was the first ...

. These licenses have been described pejoratively as viral licenses, because the inclusion of copyleft material in a larger work typically requires the entire work to be made copyleft. The term reciprocal license has also been used to describe copyleft, but has also been used for non-libre licenses (see, for example, the Microsoft Limited Reciprocal License). Free content and software licenses without the share-alike requirement are described as permissive licenses.

Creative Commons

As with all six licenses in the current Creative Commons suite, CC Attribution-ShareAlike and CC Attribution-NonCommercial-ShareAlike require attribution. According to Creative Commons, the advantage of this license is that future users are not able to add new restrictions to a derivative of your work; their derivatives must be licensed the same way. The 3.0 and 4.0 version of the ShareAlike licenses include a compatibility clause, allowing Creative Commons to declare other licenses as compatible and therefore derivatives may use these instead of the license of the original work.

Version history

Over the years, Creative Commons has issued 5 versions of the BY-SA and BY-NC-SA licenses (1.0, 2.0, 2.5, 3.0 and 4.0). *Attribution-ShareAlike Version 1.0 Generic and Attribution-NonCommercial-ShareAlike Version 1.0 Generic – Released December, 2002 *Attribution-ShareAlike Version 2.0 Generic and Attribution-NonCommercial-ShareAlike Version 2.0 Generic – Released May, 2004 *Attribution-ShareAlike Version 2.5 Generic and Attribution-NonCommercial-ShareAlike Version 2.5 Generic – Released June, 2005 *Attribution-ShareAlike Version 3.0 Unported and Attribution-NonCommercial-ShareAlike Version 3.0 Unported – Released March, 2007 *Attribution-ShareAlike Version 4.0 International and Attribution-NonCommercial-ShareAlike Version 4.0 International – Released November, 2013

References

{{intellectual property activism Public copyright licenses Copyleft Creative Commons vi:Giấy phép Creative Commons#Chia sẻ tương tự

Copyleft

Creative Commons

Version history

See also

References