According to UNESCO, Open Educational Resources are "learning, teaching and research materials in any format and medium that reside in the public domain or are under copyright that have been released under an open license, that permit no-cost access, re-use, re-purpose, adaptation and redistribution by others." OER freely grant permission to engage in the "5R" activities as described by David Wiley:
- Retain – make, own, and control a copy of the resource (e.g., download and keep your own copy)
- Revise – edit, adapt, and modify your copy of the resource (e.g., translate into another language)
- Remix – combine your original or revised copy of the resource with other existing material to create something new (e.g., make a mashup)
- Reuse – use your original, revised, or remixed copy of the resource publicly (e.g., on a website, in a presentation, in a class)
- Redistribute – share copies of your original, revised, or remixed copy of the resource with others (e.g., post a copy online or give one to a friend)
OER include not only open textbooks, but also lesson plans, lectures, videos, quizzes, and other educational materials.