Teaching online is different. In this report we attempt to explain why. This report arises from the #Openteach: Professional Development for Open Online Educators project, which is funded by the National Forum for the Enhancement of Teaching and Learning in Higher Education. In this project we plan to uncover and promote the keys to effective online teaching practice, while recognising that effective teaching is an art, craft and science. We aim to harness this knowledge to support the professional learning of online educators. Ultimately we want to support online students to learn online by helping and inspiring their educators. This report was developed to help lay a foundation for the project through a critical analysis of relevant literature.