Medicare is a federal program that pays for covered health care services of qualified beneficiaries. It was established in 1965 under Title XVIII of the Social Security Act to provide health insurance to individuals aged 65 and older, and it was expanded in 1972 to include permanently disabled individuals under the age of 65. The program is administered by the Centers for Medicare and Medicaid Services (CMS), but individuals enroll in Medicare through the Social Security Administration. CMS also contracts with private entities to provide certain services, such as claims processing, auditing, and quality oversight.
Medicare serves approximately one in six Americans and virtually all of the population aged 65 and older. In 2020, the program will cover an estimated 63 million persons (54 million aged and 9 million disabled). All beneficiaries are entitled to the same coverage regardless of income or medical history. Funding for Medicare benefits is considered mandatory spending and is not subject to the annual congressional appropriations process.
Source: Medicare Overview