The United Nations Educational, Scientific and Cultural Organization defines Open Educational Resources (OER) as "teaching, learning and research materials in any medium – digital or otherwise – that reside in the public domain or have been released under an open license that permits no-cost access, use, adaptation and redistribution by others with no or limited restrictions."
According to the Community College Consortium for Open Educational Resources, "Open licensing does not replace copyright. Open licenses work with copyright to promote shared use. This changes the copyright from “all rights reserved” to “some rights reserved.”
"Creative Commons: A User Guide" by Simone Aliprandi, Creative Commons Attirubtion-ShareAlike 3.0 Unported.
There are many materials students and faculty can freely access online, including library resources. Only materials that have an open license or are in the public domain are OERs. This is because OERs must be open as defined by the 5R's:
The 5 Rs of Open