This document provides a guide to Open Educational Resources (OERs). It begins by defining OERs and discussing their core attributes. It then outlines the types of OERs that exist, where to find them, and the advantages of using and developing OERs for teaching, learning, and research. Finally, it addresses some challenges around OERs and provides guidance on developing OERs, including considerations around content sharing and maximizing re-use. The guide is intended to answer questions around what OERs are, how to develop them, and why one should engage with them.