Like any massive insurance enterprise, Medicare is confusing. Medicare.gov offers hundreds of pages of explanation, but luckily the basics of the program aren’t difficult to grasp. As the cliché goes, however, the devil is in the details.

Medicare has four basic parts: A, B, C, and D. Taken together, Parts A (hospital care), B (doctors, medical procedures, equipment), and D (prescription drugs) provide basic coverage for Americans 65 and older. What’s relevant for this article is what these parts don’t cover, such as deductibles, co-pays, and other medical expenses that could wipe out your savings should you become seriously ill. That’s where Part C comes in. Also known as Medicare Advantage, it’s one of two ways to protect against the potentially high cost of an accident or illness. The other option is Medicare Supplement Insurance, also called Medigap coverage. Here’s a look at the two options.

Medicare Supplement Insurance, also called Medigap coverage, protects people who buy traditional Medicare against many of the additional costs a patient might pay. In return, Medigap charges a premium in addition to what the person already pays for Medicare Parts A (many people get this free), B, and D.

Just to make life truly confusing, the various options offered by Medigap are also sorted by letter. The choices are Plans A, B, C, D, F, G, K, L, M, and N. What these plans include is standardized by Medicare. The cost for them can vary, however, so it’s worth shopping around. Joseph Graves, insurance agent and founder of “I Hate Buying Insurance,” says many people enroll in Plan F, the most expensive choice, because it covers nearly all the gaps. A person with Plan F coverage will have few or no out-of-pocket expenses, however, by the end of 2019, plan F will no longer be available to new Medicare enrollees.

[Important: Medigap policies will cover you whenever you see any doctor or facility that takes Medicare. If the doctor or facility does not accept Medicare patients, Medigap won’t cover any of those costs, even though it is a private insurance policy.]

A Medicare Advantage Health Plan (Medicare Part C) may provide more help at a lower cost than traditional Medicare plus Medigap. Instead of paying for Parts A, B, and D, a person would enroll through a private insurance company that, in many cases, covers everything provided by Parts A, B, and D and may offer additional services. The beneficiary would pay the Medicare Advantage premium along with the Part B premium in most cases.

Medicare Advantage Health Plans are similar to private health insurance plans. With most plans, services such as office visits, lab work, surgery, and many others are covered after a small co-pay. Depending on what’s available regionally, plans could offer HMO or PPO network plans and place a yearly limit on total out-of-pocket expenses.

Also, like private plans, each…