As information and communication technology (ICT) plays an increasingly significant role in today's networked society, the virtual world has attracted attention from more and more researchers across different disciplines. This chapter addresses the fundamental question of why online gaming research is important, including its technological importance, its social importance, and its organizational importance. It describes the nature of multiplayer online games (MOGs), including their origins, features, and globalization. The chapter focuses on MOG players, including their types and characteristics and examines five social dynamics exhibited in MOGs: presence, communication, collaboration, conflict and competition, and community. The chapter reviews major empirical methodologies used in MOG studies and explores electronic sports as a potential future direction for MOGs. It discusses the implications of MOG studies, including implications for scholars in education, human–computer interaction, and information science, research gaps in the existing literature, and research opportunities in the future. The chapter also presents an overview of key concepts discussed in this book.