AttributionShareAlike

Attribution-ShareAlike, often abbreviated as CC BY-SA, is a Creative Commons license that allows others to copy, redistribute, remix, transform, and build upon a work for any purpose, including commercial use, provided two main conditions are met: attribution to the original author and the licensing of derivatives under the same or a compatible ShareAlike license. This makes it a copyleft license intended to keep adaptations open and freely reusable.

The key requirements are attribution and the ShareAlike condition. In practice, users must give appropriate credit, provide a link to the license, and indicate if changes were made. Any derivative works must be distributed under the same CC BY-SA terms (or a compatible license). The license also specifies that the rights granted are global and royalty-free, and that no additional restrictions can be added beyond those in the license.

Use and impact: CC BY-SA is widely used for open-content projects and media, including text, images, music, and software, because it maximizes reuse while ensuring that new creations remain open under the same terms. It is compatible with other Creative Commons licenses in certain circumstances and has been adopted by major collaborative projects such as Wikipedia. The license does not cover trademarks, patents, or privacy concerns, and it does not waive moral rights where they exist in a jurisdiction. License version differences (such as 3.0 vs. 4.0) address international applicability and modernizing terms, but the core obligations—attribution and ShareAlike—remain central.