Taking its cue from canonical performance studies scholarship, this chapter defines performance, performativity and the performative. Because of the broad scope of these terms, the chapter is organized in clusters around specific themes. It starts with a discussion of performance as repetition and re-enactment. Then, the chapter illuminates some of the main positions in the debate about liveness and mediation in performance. The chapter also discusses how adopting a broader definition of performance changes traditional understandings of the role of audience and spectatorship. Finally, the chapter provides an overview of the terms performance, performativity and the performative in relationship to each other, explaining where they intersect and differ.