This chapter offers a comprehensive, policy-oriented survey of the global history and development of antitrust. It begins by clarifying core concepts—monopoly, mechanisms of dominance, and market implications—and traces the emergence of modern competition law from the late nineteenth century to contemporary frameworks across the United States, Europe, and Asia. Building on this historical foundation, the chapter examines institutional architectures for cross-border cooperation, including bilateral agreements, regional arrangements, and multilateral fora that enable information sharing, coordinated remedies, and converging enforcement practices. To ground the discussion, we analyze representative cases that shaped doctrine and policy: U.S. conduct and platform cases, EU actions at the interface of SEPs and competition, and emblematic Asian matters in e-commerce and messaging ecosystems. These case studies illuminate recurring issues—bundling, self preferencing, exclusionary contracting, data advantages, and privacy-competition interactions—and how legal standards adapt as technology and markets evolve. The chapter then turns to the digital economy’s distinctive challenges: data-driven market power, multisided network effects, ecosystem competition, and cross-border integration that strains traditional tools for defining markets and assessing power. In response, we outline a modernisation agenda: clearer treatment of data monopolies, dynamic market assessment beyond static shares, enhanced international and cross sectoral coordination, and the rise of “computational antitrust” that leverages data analytics and algorithmic audits to support timely, evidence-based decisions. The chapter closes with practical pathways for regulators and policymakers to safeguard contestability and innovation while protecting consumer welfare in increasingly digital and globally interconnected markets.