Creative Commons license

Creative Commons is a non-profit organization defining set of predefined licenses, which can be used to define which rights author wish to retain and which to give up.
Attribution (BY) defines that original author must be credited with the copied or derived work. This is part of all CC licenses.
NonCommercial (NC) defines that work can be used only for non-commercial purposes.
NoDerivs (ND) defines, that the work can be copied only unaltered, no one is allowed to derive works from the original work.
ShareAlike (SA) defines, that derived work must be shared under exactly the same license, under which it was obtained.
Following six combinations are available:
CC-BY Creative Commons Attribution License - work can be freely copied and altered by anyone, but the original author must be credited with the derived work.
CC-BY-NC Creative Commons Attribution NonCommercial License - work can be freely copied and altered only for non-commercial purposes. Original author must be credited.
CC-BY-ND Creative Commons Attribution NoDerivs License - work can be freely copied, must must not be altered. Original author must be credited.
CC-BY-SA Creative Commons Attribution ShareAlike License - work can be freely copied and altered, but must be shared under the same license in which it was obtained. Original author must be credited.
CC-BY-NC-SD Creative Commons Attribution NonCommercial NoDerivs License - work can be used only for non-commercial purposes and it must not be altered. Original author must be credited.
CC-BY-NC-SA Creative Commons Attribution NonCommercial ShareAlike License - work can be freely used for any non-commercial purposes, but must be shared under the original license under which it was obtained. Original author must be credited.

Related help topics

Licenses and author rights