Copyleft - Creative Commons

From MITVWiki

Creative Commons defines the spectrum of possibilities between full copyright — all rights reserved — and the public domain — no rights reserved. Offering your work under a Creative Commons license does not mean giving up your copyright. It means offering some of your rights to any member of the public but only on certain conditions.

Share, reuse, and remix — legally.

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.

What conditions? You can find an overview of the Creative Commons licenses here. All of the licenses require that you give attribution in the manner specified by the author or licensor.