Gravel is a loose mixture of small stones and pebbles, usually ranging from the size of a pea to about as big as a grape. You'll find gravel covering driveways, parking lots, and country roads, where it crunches satisfyingly under your feet or bicycle tires.

Gravel forms naturally when larger rocks break down over time through weathering and erosion, or it can be made by crushing bigger rocks in quarries. Unlike smooth pavement, gravel allows water to drain through it, which is why people use it for driveways and garden paths. It's cheaper than concrete or asphalt, though it can shift around and sometimes needs to be raked back into place.

The word can also mean coarse sand or small fragments. Geologists might describe a gravelly riverbed, while a person with a scratchy, rough-sounding voice might be said to have a gravelly voice, like some radio announcers or blues singers.

When gravel gets kicked up by a car's tires, those little stones can ping against the underside of the vehicle or chip a windshield. That's why gravel roads often have signs warning drivers to slow down, and why following too closely behind another car on a gravel road can leave you peppered with flying pebbles.