Medicare is the health insurance program administered by the federal Centers for Medicare & Medicaid Services (CMS) for people 65 years of age or older, people of any age with permanent kidney failure, and some disabled individuals under age 65. Although Medicare may pay a large part of your health care expenses, it does not pay for them all. Some services and medical supplies are not fully covered. A handbook titled Medicare and You is available free from any Social Security office. The handbook provides a detailed explanation of Medicare.