OERs are not copyright-free. Instead, they are available for use under Creative Commons or similar open licenses. These licenses grant permission to Retain, Reuse, Revise, Remix, and Redistribute resources.
There are six creative commons licenses:

These licenses are comprised of a combination of four features:
BY = Attribution
You may distribute, remix, tweak, and build upon your work but must credit the author
NC = Non-Commercial
You may only use the work for non-commercial purposes
SA = Share-Alike
You must license your revised or remixed work under the identical terms
ND = No Derivatives
You are free to use and distribute the work but may not revise or remix it
Read more about Creative Commons Licenses.
Visit our Copyright Guide to learn more about copyright at Red Deer Polytechnic.