improving access, coverage and quality of health services depends on the ways services are organized and managed, and on the incentives influencing providers and users. in market-based health care systems, for example such as that in the united states, such services are usually paid for by the patient or through the patient's health insurance company. other mechanisms include government-financed systems (such as the national health service in the united kingdom). in many poorer countries, development aid, as well as funding through charities or volunteers, help support the delivery and financing of health care services among large segments of the population.