Health Insurance is insurance against the risk of incurring medical expenses among individuals. By estimating the overall risk of health care and health system  expenses among a targeted group, an insurer can develop a routine finance structure, such as a monthly premium or payroll tax, to ensure that money is available 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.