This chapter provides an overview of the Digital Markets Act (DMA) and its role within the competition law framework. It first sets out the background and policy considerations that led to its adoption. It illustrates the extent to which the objective of promoting contestable and fair digital markets complements traditional competition law. This chapter then analyses the notion of gatekeeper and the criteria used to identify them. The chapter deals with the key obligations and prohibitions imposed on designated gatekeepers. It highlights how these rules operate as ex ante safeguards. Finally, the chapter addresses the enforcement structure.