This chapter introduces the board’s pivotal role in corporate governance and outlines the core responsibilities it fulfills: control, service, and resource dependence. It contrasts the one-tier and two-tier board models, explaining how the latter, prevalent in Continental Europe, separates oversight (supervisory board) from management (management board) to enhance accountability and reduce conflicts of interest. The chapter also reviews key theoretical frameworks including agency theory, resource dependence, stakeholder theory, and the behavioral approach to explain how boards function and how their effectiveness is shaped by both structural and interactional factors.