Abstract
In the clinical setting, the focus is traditionally on individual patients after they become sick or injured. In contrast, public and population health focus on groups of patients or the public at large. These can be as small as a local neighborhood, or as big as an entire country or region or the world. Instead of diagnosis and treatment of individuals, the goal may well be prevention of disease, identification of risk or protective factors, or promotion of the health of communities as a whole. We will begin this chapter with a discussion of public health and then shift to population health.