Medicare is health insurance for the following:

People age 65 or older.

Different Parts of Medicare:
The different parts of Medicare help cover specific services.

Medicare Part A (Hospital Insurance):
Help cover inpatient care in hospitals. Help cover skilled nursing facility, hospice, and home health care.

Medicare Part B (Medical Insurance):
Help cover doctors' services, outpatient care, and home health care. Help cover some preventive services to help maintain your health and keep certain illnesses from getting worse.

Medicare Part C (Medicare Advantage Plans like HMO or PPO):
A health coverage option run by private insurance companies approved by and under contract with Medicare. Includes Part A, Part B and usually other coverage like prescription drugs.

Medicare Part D (Medicare Prescription Drug Coverage):
 A prescription drug option run by private insurance companies approved by and under contract with Medicare.Helps cover the cost of prescription drugs. May help lower your prescription drug costs and help protect against higher costs in the future.

Medicare the official U.S government site - http://www.medicare.gov/