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 a large number of persons.
By estimating the overall risk of health care 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.