CC BY-SA is the 'copyleft' music license: derivatives must be released under the same terms, creating a self-perpetuating commons

CC BY-SA (Attribution-ShareAlike) allows any use including commercial, as long as the creator is credited and any derivative work (remix, film score, compilation) is released under the same CC BY-SA license. The ShareAlike condition is a form of ‘copyleft’ — it ensures that anyone who builds on your work passes on the same freedoms they received. This is how the Wikipedia content model works. For music, it means a remixer must release their remix under CC BY-SA, but cannot use BY-SA music in a CC BY or All Rights Reserved release. If you want your music to stay in the ‘free’ commons even as others build on it, BY-SA is the appropriate choice.

Examples

A producer releases a beat under CC BY-SA. A rapper uses it, adds vocals, releases the track → the rapper’s track must also be CC BY-SA. The rapper cannot release it as ‘all rights reserved’ or ‘CC BY-NC’.

Assessment

Explain in your own words why CC BY-SA is called ‘copyleft.’ Give one scenario where a musician would prefer BY-SA over BY, and one where they would prefer BY over BY-SA.