Creative Commons

creative commons is a set of rules created to allow creators of work more freedom when sharing their work and using other peoples. It fills in the scale between full copyright where nobody can share anything or use anything and everything is free to use and anybody can claim other peoples work as their own

Creative Commons have 6 main licensing groups, depending on how much freedom you want people to have with your work.

Attribution You let others copy, distribute, display, and perform your copyrighted work — and derivative works based upon it — but only if they give credit the way you request.

Noncommercial You let others copy, distribute, display, and perform your work — and derivative works based upon it — but for noncommercial purposes only.

No Derivative Works You let others copy, distribute, display, and perform only verbatim copies of your work, not derivative works based upon it.

Share Alike You allow others to distribute derivative works only under a license identical to the license that governs your work.

There are many other forms of copyright that can be used by combining two or more of these, as described here