"Creative Commons is a nonprofit organization that enables the sharing and use of creativity and knowledge through free legal tools.
Our free, easy-to-use copyright licenses provide a simple, standardized way to give the public permission to share and use your creative work — on conditions of your choice. CC licenses let you easily change your copyright terms from the default of “all rights reserved” to “some rights reserved.”
Creative Commons licenses are not an alternative to copyright. They work alongside copyright and enable you to modify your copyright terms to best suit your needs.
If you’re looking for content that you can freely and legally use, there is a giant pool of CC-licensed creativity available to you. There are hundreds of millions of works — from songs and videos to scientific and academic material — available to the public for free and legal use under the terms of our copyright licenses, with more being contributed every day.
For those creators wishing to opt out of copyright altogether, and to maximize the interoperability of data, Creative Commons also provides tools that allow work to be placed as squarely as possible in the public domain (About Creative Commons)."