Public health has been defined as the efforts of a community that allow a population to remain healthy. This definition is very inclusive, so elements of clinical care, health promotion and many other fields contribute to the larger discipline of public health. The profession has evolved in recent years, with the emphasis in the developed world changing from the hygiene method for control of infectious diseases to a more complex approach to address chronic disease. However, the focus in public health continues to be the population. This book provides a sample of fields that contribute to the public health profession. Its broad approach provides examples of the core fields of public health, including environmental health, epidemiology, biostatistics, health administration, and health behavior.