The last Monday in May is Memorial Day, a national holiday that commemorates the military servicemembers who made the ultimate sacrifice in the line of duty.

Many people think Memorial Day and Veterans Day — another national holiday honoring servicemembers — are interchangeable, but they're not. Memorial Day honors military members who have died during their service. Veterans Day, meanwhile, honors all veterans who have served in the military, living or dead.

On Memorial Day, American flags are often placed on the graves at national cemeteries. The Department of Veterans Affairs website has resources on the proper way to display and fold flags.

How much more do you know about Memorial Day? Click through the quiz below, answer the questions and perhaps learn more about this annual holiday.