New Haven, Connecticut, United States<unk>  has been defined as "the science and art of preventing disease, prolonging life and promoting health through the organized efforts and informed choices of society, organizations,<unk>  and private, communities and individuals". Analyzing the determinants of health of a population and the threats it faces is the basis for<unk> . The<unk>  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<unk> ysical, psychological, and social well-being.<unk>  is an interdisciplinary field. For example, epidemiology, biostatistics, social sciences and management of health services are all relevant. Other important sub-fields include environmental health, community health, behavioral health, health economics,<unk>  policy, mental health, health education, health politics, occupational safety, disability, oral health, gender issues in health, and sexual and reproductive health.<unk> , together with primary care, secondary care, and tertiary care, is part of a country's overall health care system.<unk>  is implemented through the surveillance of cases and health indicators, and through the promotion of healthy behaviors. Common<unk>  initiatives include promotion of hand-washing and breastfeeding, delivery of vaccinations, promoting ventilation and improved air quality both indoors and outdoors, suicide prevention, smoking cessation, obesity education, increasing healthcare accessibility and distribution of condoms to control the spread of sexually transmitted diseases. There is a significant disparity in access to health care and<unk>  initiatives between developed countries and developing countries, as well as within developing countries. In developing countries,<unk>  infrastructures are still forming. There may not be enough trained healthcare workers, monetary resources, or, in some cases, sufficient knowledge to provide even a basic level of medical care and disease prevention. A major<unk>  concern in developing countries is poor maternal and child health, exacerbated by malnutrition and poverty coupled with governments' reluctance in implementing<unk>  policies. From the beginnings of human civilization, communities promoted health and fought disease at the population level. In complex, pre-industrialized societies, interventions designed to reduce health risks could be the initiative of different stakeholders, such as army generals, the clergy or rulers. Great Britain became a leader in the development of<unk>  initiatives, beginning in the 19th century, due to the fact that it was the first modern urban nation worldwide. The<unk>  initiatives that began to emerge initially focused on sanitation (for example, the Liverpool and London sewerage systems), control of infectious diseases (including vaccination and quarantine) and an evolving infrastructure of various sciences, e.g. statistics, microbiology, epidemiology, sciences of engineering.
Public health
International health
Community health
Global health
Regulatory science
Environmental health
Drug policy
Drug Safety