Branches whose subject is the health of populations rather than the individual: surveillance, disease frequency measurement, the social and environmental determinants of health, and the systems that protect groups from harm. Belongs here: Public Health, Epidemiology, Biostatistics, Environmental Health, Global Health, Health Communication, Health Promotion, Hygiene and Sanitation, Injury and Violence Prevention, Maternal and Child Health, Occupational Health. Does not belong here: a branch defined by an individual lifestyle choice such as diet or exercise, grouped under the lifestyle science field, or a branch defined by financing and governance rather than population measurement, grouped under the systems and policy field.