What distinguishes OER from other freely available materials is that they are openly licensed. There are several kinds of open licenses, but most common are the Creative Commons (CC) licenses. There are four license elements that can be combined to create six different CC licenses. The elements are:
SA (Share Alike)
ND (No Derivatives)
To see the six licenses, visit the Creative Commons site.
You can also put your work into the public domain with a CC0 license:
CC0 (Public Domain)
CC licenses and other open licenses give users permission to do some or all of the following:
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." (SPARC) OER come in the form of syllabi, open textbooks, slide decks, assignments, assessment materials, and more.