Epidemiology is the study of patterns, causes, and effects of health and diseases in defined populations. It is a science that is widely used to identify risk factors for disease, investigate factors that influence exposure to them, and explore how diseases distribute in space and time. By serving as a bridge between the social, medical and biological sciences, epidemiology has proven to be vital in understanding the determinants of population health, and in developing effective public health strategies. It provides the tools for assessing the relative importance of diseases, injury and other health threats in a community.

See also: causality, evolution, emergence, agent-based modeling, proto b