Creative commons is a way of taking something you have copyrighted ownership of and giving other people specific, limited ways of using it.
Let’s say I make a bunch of artwork for a game I’m making. I like the idea of other game creators being able to use some of my artwork, because I want to see more games made. But I don’t like the idea of someone else making money off my artwork. Then I can put my art up under a creative commons noncommercial license, which basically says ‘you can use this thing I made, but not for anything you end up selling for money’. Now hobbyists and people who make youtube videos and free Flash games can use my art, but the next Assassin’s Creed can’t.
Or perhaps I’m fine with you making money, but I want other people to know where the art came from – maybe I’m trying to increase my prestige as an artist but don’t care about money right now. Then I could use a creative commons attribution license to say “you can use my work for whatever you want, but you have to credit me in a visible way”.
Or perhaps I want to encourage other people to share *their* works this way. Then I could use a creative commons share-alike license to say “hey, you can do whatever you want, but you have to *also* let people do whatever *they* want with anything you make using my stuff”.
In all of these cases, I’m using my copyright – if I didn’t have one, I couldn’t tell you how you can or can’t use my stuff – but I’m choosing to give you rights I didn’t have to.
If you own the copyright to a work, it means you get to decide the terms under which other people may use that work, aside from the basic rights they already have under law (fair use and so on).
If you choose to give people additional rights to use your work, you can allow or deny requests on a case-by-case basis but that’s not feasible when you might have millions of requests. So you might write up a contract that specifies what uses you do and don’t allow – the copyright license. But rather than hire a lawyer to write up that contract, there are plenty of pre-written contracts you can use ‘off the shelf’ to assert your intentions. Creative Commons is one set of licenses you can use, that in general allow others to use some of the work you created in works of their own, with some conditions attached.
Creative Commons isn’t different from “regular copyright”, it’s just one of many mechanisms you can use to extend the rights you grant to others, beyond the default enshrined in law.
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