Online Education is well suited to health professional education (HPE) due to a combination of features including flexibility, accessibility, yield, and personalisation ability. As such, there is a growing appetite for health professional education programs to be delivered either in part, or in full, via online methods. Our understanding of the pedagogical underpinnings of digital learning tools and techniques has rapidly advanced in recent years, significantly accelerated by COVID-19. However, given the recency and speed of these academic developments, many health professional educators remain unfamiliar with the nuances of the tools and techniques, their evidence base, and the practicalities of designing and delivering these learning experiences in a best-practice manner. This introductory chapter begins by examining the definition and ways of classifying online education. It then outlines the potential opportunities for health professional educators who embrace online learning and balances this against some of the challenges of online education. It concludes by summarising the key educational learning theories that can be leveraged in online learning and thus result in more effective learning experiences.