Epidemiology plays an all-important role in many areas of medicine, from discovering the relationship between tobacco smoking and lung cancer, to documenting the impact of diet, the environment, and exercise on general health, to tracking the origin and spread of new epidemics such as Swine Flu. It is truly a vital field, central to the health of society, but it is often poorly understood, largely due to misrepresentations in the media. In this Very Short Introduction, an internationally recognized authority on epidemiology, Dr. Rodolfo Saracci, provides a wealth of information on this key...