Creative Commons is a nonprofit organization that works to increase the amount of creativity (cultural, educational, and scientific content) available in “the commons” — the body of work that is available to the public for free and legal sharing, use, repurposing, and remixing.
Creative Commons License Information
"Creative Commons provides the legal and technical infrastructure essential to the long-term success of OER, making it possible for educational resources to be widely accessible, adaptable, interoperable, and discoverable."
Source: CC Wiki
The American Library Association's guide to fair use and its limitations under current copyright law.