Public health has been defined as "the science and art of preventing disease”, prolonging life and improving quality of life through organized efforts and informed choices of society, organizations, public and private, communities and individuals.Analyzing the determinants of health of a population and the threats it faces is the basis for public health.The public can be as small as a handful of people or as large as a village or an entire city; in the case of a pandemic it may encompass several continents. The concept of health takes into account physical, psychological, and social well-being. As such, according to the World Health Organization, it is not merely the absence of disease or infirmity and more recently, a resource for everyday living.
Public health is an interdisciplinary field. For example, epidemiology, biostatistics, social sciences and management of health services are all relevant. Other important subfields include environmental health, community health, behavioral health, health economics, public policy, mental health, health education, occupational safety, gender issues in health, and sexual and reproductive health.
Public health aims to improve the quality of life through prevention and treatment of disease, including mental health. This is done through the surveillance of cases and health indicators, and through the promotion of healthy behaviors. Common public health initiatives include promotion of handwashing and breastfeeding, delivery of vaccinations, suicide prevention, and distribution of condoms to control the spread of sexually transmitted diseases