Creative Commons isn't one license, it's six. There's a handful of clauses that can be mixed and matched to form a license: * BY: Attribution requirement, ever

Creative Commons isn't one license, it's six. There's a handful of clauses that can be mixed and matched to form a license: * BY: Attribution requirement, every CC license has this * SA: Share-alike, aka "copyleft", RMS-style "virality"[0] but without a source code requirement since that is impractical outside of software. * NC: NonCommercial, license only covers not-for-profit usecases and filesharing * ND: License does not allow derivative works These can be combined like so: * CC-BY * CC-BY-SA <- This one was used by StackOverflow! * CC-BY-ND * CC-BY-NC * CC-BY-NC-SA * CC-BY-NC-ND Only the first two are "RMS compatible" licenses. [0] Copyright is already viral, share-alike/copyleft clauses just patch the virus to attack itself. It's the "treating your leukemia with HIV" of licensing.