Part A

Covers medically necessary services such as inpatient hospital care, critical care, hospice and skilled long term care.

Part B

Covers services such as outpatient care, your doctor visits and some physical therapy.  Part B is not free and you will have to pay a premium to receive this coverage. 

Part C

Known as the "Medicare Advantage Plans", Medicare Part C is health coverage through private insurance companies that are approved by Medicare which include policies such as PPO and HMO. 

Part D

Offers prescription drug coverage to Medicare beneficiaries in an effort to lower the costs of prescription drugs.  Again, this plan is provided by private insurance companies that are approved by Medicare.