Creative Commons licensing is at the heart of the OER movement. CC allows creators to retain copyright while licensing their work to others and granting them specific rights in the use of their work.
To tell if something has a Creative Commons license, look for the words "Creative Commons" and a statement about how the material may be used, or an icon like one of those below:
See the Creative Commons website for more info. For help with selecting the correct license, try Creative Commons' License Chooser.