If you’re just about to become eligible for Medicare, you may be wondering how your Medicare coverage works and what benefits are included. Medicare is a federal program, managed by the Centers for Medicare & Medicaid Services, that provides health insurance to eligible United States citizens and legal permanent residents of five or more continuous years. You’re eligible for Medicare if you’re 65 or older or under 65 through disability. You may also qualify for Medicare at any age if you have end-stage renal disease requiring dialysis or a kidney transplant, or amyotrophic lateral sclerosis (also known as Lou Gehrig’s disease). Here’s a breakdown of how Medicare coverage works.

Medicare beneficiaries can generally get their health coverage in two ways: Through Original Medicare, the government-run program, or through a Medicare Advantage plan, offered through Medicare-contracted private insurance companies.

When you first become eligible for Medicare coverage (either by age, disability, or having the above-mentioned health conditions), you’re signing up for Original Medicare, the federal program.

Once you’re enrolled in Part A and/or Part B, you may have other Medicare coverage options available to you as well, including Medicare Part C coverage (Medicare Advantage plans), Medicare Part D coverage (prescription drug benefits), and Medicare Supplement insurance (also known as Medigap). Some of these Medicare plans work alongside Original Medicare, while other types (such as Medicare Advantage plans) are an alternative way to get your Original Medicare benefits.