Medicare Part D is Medicare's prescription drug benefit (sometimes also referred to as a PDP plan). Like Medicare Parts A and B, it is a United States federal-government program. Under Part D, the government subsidizes the costs of prescription drugs.
A Medicare Part D plan adds prescription drug benefits to Original Medicare. Each Part D plan has its own list of prescriptions that it covers. The Plan's list of covered drugs is divided into different tiers - each tier with a different cost. A qualified agent can help you sort through each plan.
Check out this blog for a breakdown of the cost of PDP plans in various states: How Much Does Medicare Part D Cost?