What is it?
Medicare is a federal health insurance program for people age 65 and older, people of any age with permanent kidney failure, and certain disabled people under age 65.

Medicare is managed by the Centers for Medicare and Medicaid Services (CMS), which is part of the Department of Health and Human Services. 

You are eligible for premium–free Part A if you are age 65 or older and you or your spouse worked and paid Medicare taxes for at least 10 years (earning 40 quarters/credits).