Health insurance covers some of or all the cost of treating an insured person's illnesses or injuries. In some cases, it pays for preventive care, such as annual physicals and diagnostic tests. You may have health insurance as an employee benefit from your job or, if you qualify, through the federal government's Medicare or Medicaid programs. You may also buy individual health insurance directly from an insurance company or be eligible through a plan offered by a group to which you belong. As you do with other insurance contracts, you pay premiums to purchase coverage and the insurer pays some of or all your healthcare costs, based on the terms of your contract.