Creative Commons licenses give everyone from individual creators to large institutions a standardized way to grant the public permission to use their creative work under copyright law. From the reuser’s perspective, the presence of a Creative Commons license on a copyrighted work answers the question, “What can I do with this work?”
There are six different license types, listed from most to least permissive:
CC0 (aka CC Zero) is a public dedication tool, which allows creators to give up their copyright and put their works into the worldwide public domain. CC0 allows reusers to distribute, remix, adapt, and build upon the material in any medium or format, with no conditions.