"Open Educational Resources 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 repurposing by others. OER include full courses, course materials, modules, textbooks, streaming videos, tests, software, and any other tools, materials, or techniques used to support access to knowledge." William and Flora Hewlett Foundation
OER are released under either the Public Domain or under a Creative Commons License.
Public Domain items are those in which either:
Creative Commons are licenses that allow creators to share their works in specific ways without relinquishing copyright. These licenses allow people to use the works without contacting the creator.