An aerosol is a collection of tiny particles or liquid droplets suspended in air or gas. When you spray air freshener, use a can of whipped cream, or see mist rising from a waterfall, you're looking at an aerosol: countless microscopic bits floating through the air.

Scientists use aerosol to describe everything from fog and clouds to smoke and spray paint. Even your breath on a cold morning creates a temporary aerosol of water droplets.

The spray cans you might use for paint or bug spray are called aerosol cans. They work by storing the product under pressure with a propellant gas. When you press the button, the pressure forces the liquid out through a tiny nozzle, breaking it into a fine mist that spreads evenly.

Aerosols matter in surprising ways. Clouds are aerosols of water droplets that affect weather and climate. Air pollution often takes the form of aerosols that can harm your breathing. Even cooking creates aerosols: the delicious smell of bacon floating through your kitchen comes from tiny particles of fat suspended in air, carrying flavor molecules to your nose.