Open Access (OA) is a term applied to research outputs (articles, presentations, conference papers etc.) that have been made publicly available without restriction, providing another route to access academic content.
In practice, they can be books, journals, websites, courses, videos, blogs, podcasts or anything that instructs students and is freely available for sharing.
OERs also have the advantage of being completely free to use and re-use, as long as due credit is given in the references.
Please see below for the best places to source OERs: