This document provides an overview of open educational resources (OER). It defines OER as teaching, learning and research materials that reside in the public domain or are released with an open license. The document discusses the need for OER, their advantages such as lower costs and improved access, and challenges around quality assurance and sustainability. It also outlines the history of OER and describes various types of resources. Additionally, the document lists several major OER initiatives and institutions in India that develop and host open educational content and platforms.