• Non-profit organisation that produces copyright licenses that are free and allow the holder to reserve some rights and waive others.
• Gives more freedom to modify and edit "copyrighted" material.
Types of Creative Commons licenses:
• Attribution (by): Licensees can do whatever they want to the work as long as they give credit to the author/licensor.
• Non-commercial: Licensees can do whatever they want to the work as long as it's for non-commercial use.
• No derivative works: Licensees can copy, display and distribute works but not alter it.
• Share-alike: The work has to be licensed under the same or compatible license as the original.
• A play on the word "copyright".
• Similar to share-alike Creative Commons license, it is acceptable to distribute, modify, and copy the work as long as the new version is bound by the same license.
• For example, if a game was made and released for free, all other distributions, copies and modifications must also be free.
BENEFITS OF COPYLEFT
Copyright restricts expression as you can't recreate or modify/distribute other peoples' works. Copyleft allows you to do so while maintaining the right of the original author. It gives authors a say on how they want their work to be used. They may want their work freely distributed and modified. Copyright is more or less "all or nothing" whereas things like Copyleft and Creative Commons allow more freedom with how the author wants their work to be used. Copyleft allows collaboration - it's about sharing ideas and contributing to culture and creativity.
Open source software is a good example of how copyleft can be implemented successfully, e.g. Linux.
Beta versions of new programs are also helped massively by copyleft, as it allows people to build upon and improve them.