Public health is "the science and art of preventing disease, prolonging life and promoting health through the 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.
A community health worker in Korail Basti, a slum in Dhaka, Bangladesh
The WHO is the predominant agency associated with global health.
Newspaper headlines from around the world about polio vaccine tests (13 April 1955)
A Public Health Prayer - Dr Edmond Fernandes
Health has a variety of definitions, which have been used for different purposes over time. Health can be promoted by encouraging healthful activities, such as regular physical exercise and adequate sleep, and by reducing or avoiding unhealthful activities or situations, such as smoking or excessive stress. Some factors affecting health are due to individual choices, such as whether to engage in a high-risk behavior, while others are due to structural causes, such as whether the society is arranged in a way that makes it easier or harder for people to get necessary healthcare services. Still, other factors are beyond both individual and group choices, such as genetic disorders.
Donald Henderson as part of the CDC's smallpox eradication team in 1966
Modern drug ampoules
Nurses in Kokopo, East New Britain, Papua New Guinea
Postage stamp, New Zealand, 1933. Public health has been promoted – and depicted – in a wide variety of ways.