Open Educational Resources (OER) are "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 re-purposing by others."*
OER allow users to:
According to the U.S. PIRG Education Fund and the Student PIRGS 2014 report, Fixing the Broken Textbook Market:
If your textbook is online, you can start using it from the first day of class – no need to provide extra time for students to buy a copy.