In the United States and Canada, the term doctor describes all medical practitioners holding a professional medical degree. The American Medical Association, established in 1847, as well as the American Osteopathic Association, founded in 1897, both currently use the term physician.
A physician, medical practitioner, medical doctor, or simply doctor, is a professional who practices medicine, which is concerned with promoting, maintaining, or restoring health through the study, diagnosis, and treatment of disease, injury, and other physical and mental impairments to the body.
In the United States, Medicare is a single-payer, national social insurance program administered by the US federal government since 1966, currently using about 30–50 private insurance companies across the United States.