OER stands for open educational resources. While there are many definitions of what constitutes an open educational resource, the Scholarly Publishing and Academic Resources Coalition (SPARC) defines them as "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." For more information on what you can/can't do with OER, see the OER Mythbusting page on this guide.
Created by Blink Tower in Cape Town, South Africa for a competition in 2012, this short introductory video describes the importance of the Open Education movement.
For more information, check out EDUCAUSE's 7 Things You Should Know About Open Educational Resources.