Medicare is a government-run system that provides health care coverage to senior citizens. American citizens and permanent residents aged 65 or older are eligible for Medicare if they or their spouse has worked for at least ten years in Medicare-covered employment. Those under 65 may qualify if they have permanent kidney failure requiring dialysis or transplant. Disabled people who have received Social Security benefits for two years may also be eligible.

Traditional Medicare coverage is split into two parts -- Part A, which covers hospital stays, and Part B, which helps pay for doctor visits and outpatient hospital visits. Private Medigap plans are available to supplement traditional Medicare. Some seniors avoid traditional Medicare and instead enroll in private health insurance plans that participate in Medicare + Choice.