Creative Commons Licenses were created to open up the limited permissions associated with traditional All Rights Reserved copyright. The moment an original creative work is fixed in a tangible form, the creator owns copyright of their work. This means that the creator controls all future use of that work, and unless these rights are sold or transferred to another entity, such as a publisher, anyone who would like to share or modify the work in any way needs to request permission from the creator. In cases where the creator is unknown or difficult to reach, this practice can restrict the reach of a resource.
This is where Creative Commons licenses come in--if a work is released with a set of standardized permissions selected by the creator, the creator is able to apply permissions that are more open than the standard All Rights Reserved, and users immediately know how they can use content. Once applied, a license cannot be rescinded. There are six licenses to choose from.
CC-BY: must give credit to creator
CC-BY-SA: must give credit to creator, adaptations must be shared under same terms
CC-BY-ND: credit must be given to creator, no derivatives/adaptations permitted
CC-BY-NC: credit must be given to creator, only noncommercial uses permitted
CC-BY-NC-SA: credit must be given to creator, only noncommercial use permitted, adaptations must be shared under same terms
CC-BY-NC-ND: credit must be given to creator, only noncommercial uses permitted, no derivatives/adaptations permitted
CC0: This indicates a work known to be in the public domain. Under this license, the work is released into the public domain immediately. All use is permitted.
In order to attach a license to a work, you must own the copyright. If you're not sure what Creative Commons license you want to apply, use the CC license chooser: https://creativecommons.org/choose/#
About CC Licenses. Retrieved from https://creativecommons.org/about/cclicenses/
Yergler, Nathan and Alex Roberts. Three "layers" of licenses. Retrieved from https://labs.creativecommons.org/2011/demos/license-layers/