Creative Commons is a nonprofit organization that facilitates the decision of authors to give the public permission to share and use their works. Creative Commons enables "the sharing and use of creativity and knowledge through free legal tools".
There are six different types of Creative Commons licenses. The licenses are an alternative to the default "all rights reserved" copyright restrictions which apply automatically at the moment of a work's creation, by allowing authors to apply "some rights reserved" coverage.
For a description of each license type and the terms and conditions of permissible usage, visit http://creativecommons.org/licenses/