ABSTRACT The increased tendency towards the open education movement and the widespread use of Open Educational Resources (OER) demonstrate the potential value of sharing and reusing free digital resources among educational communities. Effective OER management, essential for all educational digital libraries, facilitates the reuse, retention, revision, remixing, and redistribution of OER. It also requires proper identification of OER. The purpose of this paper is to introduce different types of OER to digital libraries. A hybrid approach was taken which incorporated a systematic review of published articles and interviews with domain experts and a preliminary list of OER types was extracted, completed, categorised, and approved. As a result of this research, more than 90 OER types have been introduced and divided into three categories including educational content, software, and complementary materials. Identifying various types of OER in each category not only allows for better use of these resources to improve educational practices but also begins to provide an infrastructure for both human and machine use.