Health insurance is an insurance that covers the whole or a part of the risk of a person incurring medical expenses, spreading the risk over numerous persons. By estimating the overall risk of health risk and health system expenses over the risk pool, an insurer can develop a routine finance structure, such as a monthly premium or payroll tax, to provide the money to pay for the health care benefits specified in the insurance agreement.The benefit is administered by a central organization such as a government agency, private business, or not-for-profit entity.