In the United States, Medicare is a single-payer, national, social insurance program administered by the U.S. federal government since 1966, currently using about 30–50 private insurance companies across the United States under contract for administration. Medicare provides health insurance for Americans aged 65 and older who have worked and paid into the system through a payroll tax. It also provides health insurance to younger people with some disability status as determined by the Social Security Administration, as well as people with end stage renal disease and amyotrophic lateral sclerosis. (Excerpt from https://en.wikipedia.org/wiki/Medicare_(United_States)