Tools that "give every person and organization in the world a free, simple, and standardized way to grant copyright permissions for creative and academic works; ensure proper attribution; and allow others to copy, distribute, and make use of those works." (CC)
Creative Commons License Elements
BY - Attribution
Credit must be given to the creator
SA - Share Alike
Adaptations must be shared under the same terms
NC - Noncommercial
No derivatives or adaptations of the work are permitted
ND - No Derivatives
No derivatives or adaptations of the work are permitted