Medicare has four parts: Part A, B, C and D and one additional type of plan called Medicare Supplement (Medigap). Medicare Supplement Plans, also called Medigap Plans, are designed to help pay some of the hospital and medical costs not covered by Original Medicare, Parts A and B and are sold by private insurance companies. Generally, you have to be enrolled in Medicare Parts A and B to buy a Medigap plan and continue to pay your Part B Premium.
There are 10 Medigap plans available in every state (with the exception of Massachusetts, Minnesota and Wisconsin), denoted with a letter A, B, C, D, F, G, K, L, M and N. The benefits of each Medigap plan type are standardized across the country although prices may vary across different insurers.
To learn more, you can go to this page to watch a video on Medicare Supplement Plans.