“Medicare is the federal health insurance program created in 1965 for people ages 65 and over, regardless of income, medical history, or health status. The program was expanded in 1972 to cover certain people under age 65 who have a long-term disability. Today, Medicare plays a key role in providing health and financial security to 60 million older people and younger people with disabilities. The program helps to pay for many medical care services, including hospitalizations, physician visits, prescription drugs, preventive services, skilled nursing facility and home health care, and hospice care. In 2017, Medicare spending accounted for 15 percent of total federal spending and 20 percent of total national health spending. Most people ages 65 and over are entitled to Medicare Part A if they or their spouse are eligible for Social Security payments, and do not have to pay a premium for Part A if they paid payroll taxes for 10 or more years. People under age 65 who receive Social Security Disability Insurance (SSDI) payments generally become eligible for Medicare after a two-year waiting period, while those diagnosed with end-stage renal disease (ESRD) and amyotrophic lateral sclerosis (ALS) become eligible for Medicare with no waiting period.

Source: Issue Brief: An Overview of Medicare. Kaiser Family Foundation. February 2019. http://files.kff.org/attachment/issue-brief-an-overview-of-medicare