Single-payer health care is a term used in the United States to describe the payment of doctors, hospitals, and other health care providers from a single fund. It differs from typical private health insurance where, through pricing and other measures taken by the insurer, the level of risks carried by multiple insurance pools as well as the coverage can vary and the pricing has to be varied according to the contribution of risk added to the pool. It is often mentioned as one way to deliver universal health care. The administrator of the fund could be the government but it could also be a publicly owned agency regulated by law. Australia's Medicare, Canada's Medicare, and healthcare in Taiwan are examples of single-payer universal health care systems.

Source: Wikipedia
http://en.wikipedia.org/wiki/Single-payer_health_care