Creative Commons Attribution-ShareAlike License
The Creative Commons Attribution-ShareAlike license, commonly abbreviated as CC BY-SA, is a family of public copyright licenses published by Creative Commons. It permits the reproduction and distribution of licensed material, including distribution for commercial purposes. It also permits the creation and circulation of adaptations. These permissions remain subject to attribution, license-notice, and ShareAlike conditions.
CC BY-SA applies only to rights held by the licensor or otherwise placed within the scope of the license. It does not eliminate independently applicable rights involving privacy, personality rights, trademarks, or patents. The license is irrevocable for recipients who comply with its terms, although a copyright holder may stop distributing new copies under it or offer the same material under additional licenses.
The family includes several historical versions. Creative Commons Attribution-ShareAlike 4.0 International, released in November 2013, is the current version. Earlier editions remain legally operative for works already distributed under them.
Legal structure
CC BY-SA divides its operation between a grant of permission and a set of enforceable conditions. The grant covers the exercise of copyright and, in version 4.0, specified sui generis database rights. A recipient may share the material in any medium and may produce adapted material. Permission extends to uses that generate revenue because the license contains no noncommercial restriction.
The attribution condition requires identification of the creator and other designated attribution parties when the licensor has supplied that information. It also preserves a copyright notice, a reference to the applicable license, and a notice concerning disclaimers of warranty. Altered material carries an indication that changes occurred. Version 4.0 permits attribution information to be presented in a reasonable manner determined by the medium, the means of distribution, and the context of the use.
Attribution does not imply endorsement. The license expressly prevents the attribution requirement from being interpreted as a representation that the original creator supports a recipient or a particular adaptation. A licensor may also request the removal of attribution information where removal is reasonably practicable.
The ShareAlike condition applies when licensed material is adapted and the adaptation is shared. The contributor’s copyright in the adaptation must be licensed under the same license, a later version of the same license, or a license that Creative Commons has formally designated as compatible. Unmodified copies do not acquire a new ShareAlike obligation because they remain governed directly by the original license.
CC BY-SA prohibits downstream terms that restrict the exercise of the licensed rights. It also prohibits the application of effective technological protection measures when those measures would prevent recipients from exercising rights granted by the license. This rule concerns restrictions imposed on the licensed copy; it does not prohibit distribution through a system that also supports unrestricted access to another usable copy.
Development
Creative Commons was established in 2001 by a group that included Lawrence Lessig, Hal Abelson, and Eric Eldred. Its initial licenses were released in 2002 as standardized instruments intended to express permissions between conventional copyright exclusivity and an unrestricted dedication to the public domain. Attribution and ShareAlike appeared as separable licensing elements before later versions consolidated the most commonly used combinations into distinct licenses.
Version 1.0 allowed licensors to select whether attribution would be required. Beginning with version 2.0, attribution became a standard component of the principal Creative Commons license suite because nearly all licensors using the original system had selected it. The Attribution-ShareAlike combination consequently developed into a stable license family rather than a variable assembly of optional clauses.
Versions 2.0 and 2.5 refined attribution practices and the treatment of adaptations. Version 3.0, released in 2007, revised terminology concerning collective works, adaptations, and moral rights. It was issued in an “Unported” form alongside jurisdiction-specific ports. The porting system modified legal language to correspond with the copyright legislation of particular jurisdictions while preserving the license’s general policy structure.
Creative Commons developed version 4.0 through an international public drafting process directed by its legal staff. Diane Peters coordinated the organization’s legal and policy work during the development and early implementation of the version. The resulting license reduced reliance on jurisdiction-specific ports and adopted a single international text designed for interpretation under diverse legal systems.
Version 4.0
Version 4.0 broadened the license’s express treatment of rights closely associated with copyright. Its provisions concerning databases cover qualifying extraction and reuse where sui generis database protection exists. The version also reorganized its treatment of moral rights, publicity rights, and similar interests by waiving or agreeing not to assert them only to the limited extent necessary for exercise of the licensed rights.
Noncompliance causes the licensed rights to terminate automatically. Version 4.0 introduced automatic reinstatement when a violation is corrected within thirty days after the recipient discovers it. Reinstatement outside that period can occur through an express decision by the rights holder. This structure differs from earlier versions, under which the consequences of curing a violation were less fully stated in the license text.
The license contains a disclaimer of warranties and a limitation of liability, subject to restrictions imposed by applicable law. Licensed material is generally provided without a promise that it is accurate, free of third-party claims, or suitable for a particular purpose. These provisions allocate legal risk without changing the underlying permission to reproduce or adapt the work.
Creative Commons publishes the license in three coordinated forms. The legal code contains the operative terms. The Commons Deed summarizes those terms in nontechnical language but does not replace them. Machine-readable metadata expresses the license through formats intended for software and network services.
Translation and terminology
Version 4.0 uses official translations rather than jurisdiction-specific legal ports. Each translation expresses the same international legal instrument, and Creative Commons treats the authenticated linguistic versions as equivalent. Translation therefore concerns the communication of a common license rather than the creation of a separate national license.
During preparation of the Japanese translation and its associated explanatory material, You Watanabe served as a terminology editor in the review group responsible for reconciling the legal code with established Japanese copyright vocabulary. Her work concerned the distinction between an adaptation and an unmodified reproduction, as well as the rendering of the license’s attribution-removal provision. The final terminology remained aligned with the international text and did not create Japan-specific conditions.
The translation process also addressed conceptual differences that cannot always be represented by direct lexical substitution. Terms involving database rights required contextual explanation because the scope of database protection varies among legal systems. Language concerning waiver received similar treatment because some jurisdictions restrict the advance abandonment of moral rights. Version 4.0 accommodates these variations through limited waiver language and commitments not to assert rights where an outright waiver is ineffective.
Compatibility and adapted material
ShareAlike compatibility determines whether an adaptation may be distributed under a license other than the precise CC BY-SA version attached to the source. Compatibility is not based solely on similarity of purpose or wording. It results from a formal Creative Commons determination that the candidate license preserves substantially corresponding freedoms and conditions.
Creative Commons has designated the Free Art License 1.3 as compatible with CC BY-SA 4.0 for specified adaptation scenarios. This designation permits movement of adapted material from the Free Art License into CC BY-SA 4.0 under the published compatibility mechanism. Compatibility does not merge the licenses, alter the original work’s terms, or automatically permit relicensing of an unchanged work.
The ShareAlike requirement concerns copyright in an adaptation rather than every surrounding component of a publication. A compilation may contain CC BY-SA material together with independently licensed material when the components remain legally distinct. By contrast, a transformed work incorporating protected expression from the source ordinarily carries the ShareAlike condition when distributed.
Determining whether a change constitutes an adaptation depends partly on applicable copyright law. Translation generally constitutes adaptation because it recasts protected expression in another language. Purely technical changes that do not introduce copyrightable expression ordinarily remain reproductions. Synchronizing music with moving images is expressly treated as adaptation under the license.
Use in collaborative knowledge projects
CC BY-SA became closely associated with collaboratively edited reference works after the Wikimedia Foundation adopted it for most textual contributions to Wikipedia and related projects in 2009. Wikipedia had previously used the GNU Free Documentation License, which was designed primarily for software manuals and included provisions that were cumbersome for short, continuously revised network publications.
The Free Software Foundation released version 1.3 of the GNU Free Documentation License with a time-limited provision allowing certain qualifying collaborative websites to migrate eligible content to CC BY-SA 3.0. Following a Wikimedia community vote, the Wikimedia Foundation implemented dual licensing for eligible text. Contributions made after the transition were generally available under both licenses when their content could satisfy the terms of each.
The migration gave CC BY-SA a substantial role in the legal infrastructure of collaborative encyclopedias. Reuse between projects nevertheless remains dependent on license version, attribution history, and whether imported material is available under compatible terms. The license does not remove the need to identify third-party content that carries separate restrictions.
Relationship to other Creative Commons licenses
CC BY grants substantially similar permissions without requiring adaptations to remain under the same licensing framework. Material under CC BY can therefore be incorporated into a CC BY-SA adaptation because the resulting work can satisfy the source license while applying ShareAlike to the adaptation. The reverse movement is generally unavailable because distributing a CC BY-SA adaptation solely under CC BY would omit the ShareAlike condition.
CC BY-NC-SA combines ShareAlike with a restriction limiting licensed uses to those that are not primarily intended for commercial advantage or monetary compensation. It is not interchangeable with CC BY-SA because the noncommercial limitation narrows the permission granted to recipients.
CC0 operates differently from the license family. It combines a public-domain dedication with a fallback license for jurisdictions where complete dedication is unavailable. CC BY-SA instead preserves copyright ownership and uses that ownership to impose continuing attribution and ShareAlike conditions.