Tens of millions of Americans rely on Medicare, with most of them first becoming eligible when they turn 65. Yet there are many people who don't know much about how Medicare works or how it can protect you against expensive medical costs.

In the following slideshow, Dan Caplinger, The Motley Fool's director of investment planning, looks at 10 essential facts that everyone needs to know about Medicare. By discussing eligibility, types of coverage, requirements for signing up, and some of the financial challenges that Medicare is facing, you'll quickly learn a lot more about how you can ensure you get the healthcare you need during your retirement years.

Dan Caplinger has no position in any stocks mentioned, and neither does The Motley Fool. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.