The National Health Service (NHS) is the publicly funded national healthcare system for England and one of the four National Health Services of the United Kingdom. It is the largest and the oldest single-payer healthcare system in the world. Primarily funded through the general taxation system and overseen by the Department of Health, the system provides healthcare to every legal resident in England, with most services free at the point of use. Some services, such as emergency treatment and treatment of infectious diseases are free for everyone, including visitors.