"Open Educational Resources (OER) are teaching and learning materials that are freely available online for everyone to use, whether you are an instructor, student or self-learner. Examples of OER include: full courses, course modules, syllabi, lectures, homework assignments, quizzes, lab and classroom activities, pedagogical materials, games, simulations, and many more resources contained in digital media collections from around the world."
David Wiley summarizes how you can use (and reuse) OERs with his "5 Rs":
Source: Wiley, D. (2014). An Open Educational Reader (Ed.). Montreal: Pressbooks.
Quality is an important consideration for faculty who are thinking about making the move to OERs. Many of the OERs available go through the same rigorous peer review process as textbooks published in the traditional textbook market. In fact, some of the textbooks you'll find in places like OpenStax are the exact same textbook that has been previously published traditionally.
As when selecting any new textbook, you should evaluate OER textbooks for content and accuracy. There are many repositories that make this easier by including professor reviews on their websites. My favorite place to start is the Open Textbook Library. Books in this repository must be complete, original textbooks that are openly licensed and in use at multiple higher education institutions. These books are available for review based on the following criteria:
Basic Information on OER:
Recent Research on OER: