Learn the Basics

Medicare is made up of 4 parts.

Part A is hospital insurance.

Part A covers inpatient care at a hospital, skilled nursing facility (SNF) care, nursing home care (as long as custodial care isn't the only care you need), hospice and home health services. Part A also covers services like lab tests, surgery, doctor visits, and home health care.

Part B is medical insurance.

Part B covers two types of services. Medically necessary services or supplies are covered if needed to diagnose or treat a medical condition and that meet accepted standards of medical practice. Some preventive services such as health care are covered if to prevent illness (like the flu) or to detect it at an early stage, when treatment is most likely to work best. 

You pay nothing for most preventive services if you get the services from a health care provider who accepts assignment and to be paid directly by Medicare.

Part C or Medicare Advantage is an optional policy.

Part C is like an HMO or PPO, or other Medicare health plan that offers Medicare prescription drug coverage. You get all of your Medicare Part A (Hospital Insurance) and Medicare Part B (Medical Insurance) coverage, and Part D (Medicare Prescription Drug) coverage, through these Medicare Advantage Plans. You must have Part A and Part B to join a Medicare Advantage Plan. Enrollment is voluntary and you cannot be denied coverage.

Part D is the Medicare Prescription Drug Benefit Option.

Part D or Medicare Prescription Drug Plans add drug coverage to Original Medicare, some Medicare Cost Plans, Medicare Advantage plans that do not already include prescription drug coverage (MA-only), and Medicare Medical Savings Account (MSA) Plans. Private companies (providers) have contracted with Medicare to offer this benefit. The premium costs, deductibles and co-pays for prescription drugs will vary according to the provider's plan. Anyone enrolled in Medicare Part A and/or Medicare Part B may be able to join a Medicare Prescription Drug Plan.

Source: www.medicare.gov