Medicare is a national health insurance system administered by the federal government. It pays for people age 65 and older or who qualify due to severe disability. The Medicare program became active in 1965 under the administration of President Lyndon B. Johnson. The first individual to actually enroll in the system was former President Harry S. Truman. Medicare helps pay for certain health care expenses. Medicare is made up of several parts. Medicare Part A is often called hospital insurance. Part A is usually received at no cost as part of the taxes a person or a person's spouse had paid while working contribute to this part of Medicare. Part B is is often called medical coverage. Most people will pay for for Part B of Medicare. The premium for Part B can change annually. People who do not qualify for Medicare due to having paid enough taxes into the system may possibly be able to buy into the system. Part D is prescription coverage. Medicare Advantage is an alternative system to original Medicare. Many Medicare Advantage plans include prescription coverage.