This is the second module of Yale's online course Essentials of Global Health, introducing the field's basic vocabulary and the frameworks scholars use to define what counts as a global health issue. The lecture lays out competing perspectives, from biomedical to social-justice framings, on why some conditions get labeled global health problems and others do not. It surveys the determinants of health, including the social and economic factors that shape disease patterns across populations, and maps the landscape of key actors: national governments, the World Health Organization, NGOs, and private funders, along with how they coordinate and compete. The tone is orienting rather than argumentative, meant to equip students with concepts they will use throughout the rest of the course.