This chapter provides an overview of antitrust and competition laws (competition law). While competition law was primarily (although not exclusively) an American phenomenon for most of the 20th century, competition law is now actively enforced in more than 120 jurisdictions, encompassing all the major economies of the world. Competition law has thus become relevant to the vast majority of global business activity and significant business enterprises. While the numerous competition laws and their enforcement modalities vary widely, this chapter attempts to provide a broad overview of their most basic and recognisable features, and thereby to suggest how competition law is likely to interact with the telecommunications, internet and media sectors in any particular jurisdiction. This chapter also identifies significant competition law developments involving the telecoms, internet and media sectors in the past year.