Creative Commons (CC) licenses are open licenses available to any copyright holder or content creator to use for free. The goal is to keep creative works protected under copyright law but to make them available for use by others in a variety of ways determined by the creator.
When a CC license is applied to a copyrighted work, the author declares what can and cannot be done with that work by any user, and users know what they can do with a work without needing to ask permission.