County or city-operated outpatient health care facilities that provide a broad range of diagnostic and treatment services including primary adult and pediatric care, prenatal care, dental care and specialty medicine as well as laboratory and radiological services and allied support services like nutrition and health education. Some public clinics may also offer public health services such as immunizations and communicable disease screening and treatment. Services are available on an ability-to-pay basis and target low-income and indigent residents of the community.

Programs that provide inoculations or other prophylactic measures to prevent susceptible individuals from contracting specific diseases for which means of control have been developed including immunizations recommended specifically for newborns and young children, booster shots to prevent the occurrence of childhood illnesses in adolescence and adulthood, inoculations recommended specifically for pregnant women and immunizations against illnesses such as shingles and pneumonia for older adults.

Individuals whose ethnic background and ancestry are that of the tribal, aboriginal peoples who originated in what is now the United States. Included are Native Americans who are living on or off reservations in rural and urban areas.