OER are "teaching, learning, and research resources that reside in the public domain or have been released under an intellectual property license that permits their free use and re-purposing by others." (From The William and Flora Hewlett Foundation)
OER materials are released under an open license granting permission for everyone to do the 5Rs (Retain, Reuse, Revise, Remix, Redistribute).
OER include digital learning materials such as:
Michigan State University (MSU) Libraries OER Program Guide is licensed under a Creative Commons Attribution 4.0 International License.