As an information and communication technology, the Internet has contributed to structural changes in social life. This technology has opened up new social spaces for people to communicate across time and space, explore interests and interactions, and form and maintain relationships. Gender is a social structure that matters, but how it matters online is a topic that has intrigued researchers for the last 20 years. Research in the area of online gender interactions is multidisciplinary and addresses a variety of online forums including discussion groups, chat, instant messaging, blogs, virtual worlds and social network sites. Patterns are identified in the literature and examples of gender fluidity, gender reproduction, and a blending of gender fluidity and reproduction are presented. This paper provides a framework for understanding the multidisciplinary research on this topic and discusses how changes in online demographics and recent developments in information and communication technologies, such as social network sites, present new forums in which to explore the role of gender in online interactions.