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. It is a field that aims to protect and improve the health of populations by promoting healthy lifestyles, researching disease and injury prevention, and detecting, preventing, and responding to infectious diseases. Public health is related to global health, which is the health of populations in the worldwide context.

Public health is implemented through the surveillance of cases and health indicators, and through the promotion of healthy behaviors. It is concerned with protecting the health of entire populations, which can be as small as a local neighborhood or as big as an entire country or region of the world. Public health work spans government, business, and nonprofit sectors.

Public health is not the same as public healthcare (publicly funded health care). Public health professionals try to prevent problems from happening or recurring through implementing educational programs, recommending policies, administering services, and conducting research. Public health also works to limit health disparities and promote health care equity, quality, and accessibility.

Examples of public health work include promoting healthy lifestyles, researching disease and injury prevention, detecting, preventing, and responding to infectious diseases, and evaluating health insurance programs. Public health professionals work in various sectors, including government, business, and nonprofit organizations.

Overall, public health is an essential field that promotes and protects the health of all people and their communities. It improves our quality of life, helps children thrive, reduces human suffering, and saves money.