health insurance, system for the financing of medical expenses by means of contributions or taxes paid into a common fund to pay for all or part of health services specified in an insurance policy or the law. The key elements common to most health insurance plans are advance payment of premiums or taxes, pooling of funds, and eligibility for benefits on the basis of contributions or employment.
Health insurance may apply to a limited or comprehensive range of medical services and may provide for full or partial payment of the costs of specific services. Benefits may consist of the right to certain medical services or reimbursement to the insured for specified medical costs. Some types of health insurance may also include income benefits for working time lost because of sickness (i.e., disability leave) or parental leave.