"Open Educational Resources (OER) are teaching, learning, and research resources that are free of cost and access barriers, and which also carry legal permission for open use. Generally, this permission is granted by the use of an open license (for example, Creative Commons licenses) which allows anyone to freely use, adapt and share the resource—anytime, anywhere."--Scholarly Publishing and Academic Resources Coalition (SPARC)
Examples of OER include:
Opencontent.org states that true OER are free to access and allow for the 5R's of open content:
Making Open Educational Resources: A Guide for Students by Students by Ashlyne O'Neil; Jykee Pavo; Mikayla Bornais; Tariq Al-Rfouh; Chris Nardone; Elijah Annoh-Waithe; Lawrence Villacorte; Lorenzo Pernasilici; Marianne Kantati; Mitchel Macmillan; Mohamed Eldabagh; Norman Ha; Devin Wacheski; Anas Al-Chalabi; Dave Cormier; Brandon Mailloux; Ghanem Ghanem; Kamaal Kusow; Kristen Swiatoschik; Patrick Carnevale; Rana Kilani; Steven Shlimoon; and Zain Raza is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.