Creative Commons (CC) is a non-profit organization headquartered in Mountain View, California, United States. They are devoted to expanding the range of creative works that are available to share and build upon legally. The organization has released several copyright-licenses known as Creative Commons licenses free of charge to the public. These licenses allow creators to communicate which rights they reserve, and which rights they waive for the benefit of recipients or other creators. Each of their licenses is represented with a symbol that explains all the rights associated with the resource.
Using a Creative Commons license on open educations resources has become a mainstay for OER creators. They maintain a page with step by step instructions for how to choose a license at http://creativecommons.org/choose/.
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