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 include digital learning materials such as:
open textbooks | courses | syllabi | lectures | assignments | quizzes | lab activities | games | simulations
Learn more: What is OER?
There are many reasons instructors might want to use OER: