Part A covers hospitalization, short term inpatient rehab and hospice.
Part B covers medical expenses such as doctor‘s visits, tests, labs, home health care, and durable medical equipment, etc.
Part C is called “Medicare Advantage.” It is not a separate benefit. Part C is the part of the Medicare policy that allows private health insurance to provide Medicare benefits. These private health plans, such as HMOs* and PPOs** are known as “Medicare Advantage plans.” If you want, you can choose to get your medical coverage through a Medicare Advantage plan instead of through original Medicare.
Part D provides outpatient prescription drug coverage. It is provided only through private insurance companies that have contracts with the government.