Vapor is what you get when a liquid turns into a gas. When water boils in a pot on the stove, the bubbles rising to the surface release water vapor into the air. When you see your breath on a cold morning, that's water vapor from your lungs condensing into tiny droplets in the cool air.

Scientists use vapor to describe any substance in its gas form, especially when that substance is usually a liquid or solid at normal temperatures. The puddles on the sidewalk after a rainstorm slowly disappear because the water evaporates, turning into invisible water vapor that mixes with the air.

The word has a light, airy feeling to it. Things that vaporize seem to vanish into thin air. You might hear someone say a dream or plan vaporized when it disappeared without a trace. In some stories and movies, vaporizing something can mean destroying it so completely that almost nothing remains.

Related words include evaporate (when a liquid slowly turns to vapor) and steam (the visible mist that rises from hot water or soup). Understanding vapor helps explain weather, cooking, and why wet clothes eventually dry.