Health insurance provides coverage for medical expenses through a contract between an insurer and an individual. It offers key benefits like cashless treatment at empaneled hospitals, coverage for pre- and post-hospitalization expenses, and ambulance fees. When buying a health insurance policy, it is important to consider the age criteria, appropriate premium and coverage amounts, waiting periods, cashless hospital networks, and other clauses. Health insurance offers tax benefits under Section 80D and can help cover unexpected medical costs.