The four parts of Medicare include the following: Part A is insurance for the costs of hospitalization and hospital treatment. Most eligible seniors get this for free. Part B is optional and covers medically necessary outpatient services and care. This has a monthly premium of $170.10 for most individuals as of 2022. Part C is also called a Medicare Advantage Plan. This is for people who want a private insurance company to administer all of their Medicare services. You can choose your own provider, and you have the option to pay for services above and beyond Medicare coverage. Part D is optional coverage for prescription medicine and is available from private insurance companies. If you have a Medicare Advantage Plan (Part C) you can add Part D coverage to it. Or, you can buy it separately. The Medicare site has a search function to help people find a Part C or a Part D plan.