This article presents a new social framework for understanding the origins of trolling and its expansion from an obscure practice, limited to a handful of boards on Usenet, to a pervasive component of Internet culture. I argue that trolling originated, in the term of sociologists, as a form of boundary maintenance that served to distinguish communities of self-identified online insiders from others beyond the boundaries of their community and to drive outsiders away from their spaces. This framework can help us to better understand the transformations that trolling has undergone in the decades since its inception, as well as the persistence of misogyny and prejudice throughout the history of the practice.