This lecture introduces key concepts and perspectives in the sociology of health and illness. It discusses the problems with defining terms like health, illness, and disease, as definitions vary between disciplines, cultures, and over time. Both social constructionist and biological perspectives are examined. Social constructionism views these states as socially produced, while biological views emphasize innate factors. An interdisciplinary approach is needed, as each perspective provides insights. Definitions are contested and contextual, with implications for policy. Health, illness, and disease are complex topics with both subjective and objective aspects.