What an OER is and what it is not
The term ‘Open Educational Resources’ (OER) describes any educational resources (including curriculum maps, course materials, textbooks, videos, multimedia applications, podcasts, or any other materials designed for teaching and learning) which have been made available for use under open licenses – which means that anyone can use, adapt and redistribute them. Those materials may be available online, in print, on DVD or any other carrier.
OER are not the only educational materials to be found on the Web. Unfortunately, most resources on the Internet are closed resources, even if they are available for free. Materials that are under full copyright, or which are not accompanied by a specific license allowing anyone to copy, adapt and share them, are not Open Educational Resources. You can use these materials only within the fair use provisions or copyright exceptions in your country.
Want to know more?
Creative Commons Wiki: http://wiki.creativecommons.org/What is OER
Open Educational Resources, William and Flora Hewlett Foundation
Giving Knowledge for Free THE EMERGENCE OF OPEN EDUCATIONAL RESOURCES, Organization for Economic Co-operation and Development (OECD)
Open Education License Draft, David Wiley’s post on freedoms in OER,