Epidemiology is often described as the cornerstone science in public health. Epidemiology in public health practice uses study design and analyses to identify causes in an outbreak situation, guides interventions to improve population health, and evaluates programs and policies.

 The common practical applications of epidemiology include investigation of infectious diseases. These are done on a routine basis and are conducted by health departments to investigate common infectious diseases, particularly food borne illness, and food borne disease.

Uses of epidemiology in support of public health Epidemiology is the basic science of public health because it is the health science that describes health and disease in populations rather than in individuals, information essential for the formulation of effective public health initiatives to prevent disease and promote health in the community.