Medicare is the federal health insurance program, and it was created in 1965. This program was created to cover older Americans (those 65 years or older.) In addition, some folks with medical conditions or disabilities can get coverage from Medicare.
Most people will join Medicare when they turn 65 years old. In order to be eligible, most Americans will have to have worked for a minimum of 10 years. If you still have employer coverage when you turn 65, you will likely enroll in Medicare when you retire.