"Cultivating a New Creative Commons: Creative Commons is a non-profit organization founded on the notion that some people would prefer to share their creative works (and the power to copy, modify, and distribute their works) instead of exercising all of the restrictions of copyright law."

From the concepts page:

Creativity and innovation rely on a rich heritage of prior intellectual endeavor. We stand on the shoulders of giants by revisiting, reusing, and transforming the ideas and works of our peers and predecessors. Digital communications promise a new explosion of this kind of collaborative creative activity. But, at the same time, expanding intellectual property protection leaves fewer and fewer creative works in the "public domain"--the body of creative material unfettered by law and, to quote Supreme Court Justice Louis Brandeis, "free as the air to common use."