Medicare is a health care coverage program offered by the federal government for citizens who are 65+ years old, those who are receiving Social Security Disability Insurance, or those under the age of 65 with End-Stage Renal Disease. It is run by a federal agency called the Centers for Medicare & Medicaid Services.

Medicare consists of four parts and these are explained here in a nutshell.

Plan A
Medicare part A and B are referred to as Original Medicare, which means that these coverage costs are managed by the federal government.

Part B
Medicare Part B provides coverage for outpatient or medical services. This part covers two types of services:

• Medically necessary services
  These are services or supplies that are required for diagnosing or treating the patient. It also covers services that meet the prescribed standards of medical practice.
• Preventive services
  These include health care services required for preventing illnesses like flu or when the illnesses are detected at an early stage when treatment is most effective.

Medicare Part B also covers clinical research, durable medical equipment, ambulance services, outpatient, inpatient and partial hospitalization of mental conditions, getting a second opinion before surgery, and limited prescription medications for outpatient cases.

Part C
Most of the medical costs are covered by Original Medicare. But some people choose to opt for Medicare Advantage Plan, also known as Part C or Medicare private health plan. Part C health plans are provided by private companies but are approved by Medicare.

Medicare Advantage Plan covers all of Part A and Part B costs along with additional coverage that includes dental-, hearing-, and vision-related ailments, as well as wellness programs. For health care coverage, Medicare pays a fixed amount per month to private companies offering Part C plans, and these companies are required to abide by the guidelines set by Medicare.

Part D
This part includes prescription medicine benefits and covers outpatient prescription medicine costs. Private companies offer Part D coverage either as a stand-alone plan to those enrolled in Original Medicare or as benefits included in the Medicare Advantage Plan. Every Part D plan has a list of medications that are covered, and these are included in the formulary. If any of the medications you require are not included in the formulary, you may have to pay out of pocket, request for an exception, or file an appeal.

Some medications are not included under Medicare coverage by law. These include medications used for weight gain or loss and over-the-counter medicines.