Open educational resources (OER) are teaching and learning materials that are freely available to students, educators, and the general public. They are openly licensed so that others can adopt or reuse this material for their own purposes.
Most OERs are licensed by Creative Commons. which provides a set of statements that indicate the author's wishes regarding attribution and adaption. Specifically, CC covers these concepts.
(See OpenContent.org, UNESCO and OER Commons for the above definitions).