Part D is the name of Medicare's prescription drug coverage. It's insurance that helps people pay for prescription drugs. It is available to everyone who has Medicare. It provides protection if you pay high drug costs or have unexpected prescription drug bills. It doesn't cover all costs. You have to pay part of the cost of prescription drugs. Most people also have to pay an additional monthly cost.
Private companies provide Medicare prescription drug coverage. You choose the drug plan you like best. Whether or not you should sign up depends on how good your current coverage is. You need to sign up as soon as you are eligible for Medicare. Otherwise, there may be additional charges.
Centers for Medicare and Medicaid Services
References and abstracts from MEDLINE/PubMed (National Library of Medicine)