En español | Starting this year, one boomer will become eligible for Medicare every eight seconds. Yes, Medicare — the health insurance program run by the federal government for people 65 and older.

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If you’re fast approaching — or have just recently passed — that milestone, take heart. Medicare can be a welcome birthday present, especially if you take time to understand the different parts of the program and the wealth of health care resources it provides.  

Use this AARP guide as an introduction. We promise that by the end of our tour you will understand the difference between Medicare Parts A, B, C and D.) For a deeper dive into Medicare, follow the links to additional resources and tips. But first things first:

What is Medicare?
Medicare is a federal health insurance program for those 65 and older. It was signed into law by President Lyndon B. Johnson in July 1965 as a way to help older adults pay their medical expenses. (Medicaid, the federally run health insurance program for low-income people, was created at the same time.)

Over the years, Medicare has been expanded to provide coverage for some younger people with disabilities, and for people with end-stage kidney disease. In 2003, President George W. Bush established Medicare Part D, a program designed to help people with Medicare pay for their prescription drugs.

Before turning 65, most people get health insurance through group plans offered by their employer or their spouse’s employer. People who are self-employed or who don’t have health insurance through their job may buy individual policies on their own.

When you turn 65, however, you’ll likely be eligible for one of the largest group health plans in the world. Medicare can be used as your sole health insurance coverage or as companion or backup coverage to insurance you have through your employer, spouse, former employer or union.

Medicare consists of several plans or "parts":

• Parts A and B are often referred to as Original, or Traditional, Medicare. Part A helps pay your hospital bills, and most people have paid for their Part A premiums through payroll taxes while working. Part B helps pay for doctor visits and other medical services, including screenings for heart disease, diabetes and some types of cancer.

• Part C plans, also known as Medicare Advantage plans, are Medicare-approved plans offered by private insurance companies. Part C plans are an alternative to Original Medicare. Along with covering doctors and hospitals, they often cover prescription drugs, too.

• Part D plans are Medicare-approved private plans that help people who have Parts A and B to pay for prescription drugs.

Keep in mind that Medicare doesn’t cover all of your health care costs. Many services (such as routine dental and vision care) are not covered by Medicare. And unless you have additional insurance or qualify for low-income assistance, even with Medicare, you will be paying some premiums, deductibles and copays.