What is steam? Steam is water as a gas. Steam is invisible.

Steam

Steam from a kettle. The steam is the invisible gas just at the kettle spout. What you can see is condensed steam (liquid water droplets). So most people actually refer to the wrong thing when they say 'steam'.

Steam is the form of water that is produced when liquid water boils at 100°C. It is invisible. However, because it is so hot it will scald you.

Steam is the gas in the bubbles coming off of boiling water. They make up the bubbles inside the water, too.

What most people call steam is not steam at all, but tiny drops of liquid water. These form because the invisible steam gas is soon cooled when it comes into contact with the air. When water vapour (gas) condenses into liquid water it makes tiny droplets.

If you look carefully at this picture you will see there are no droplets next to the kettle spout. That is steam. The white cloud is water droplets.

Steam bubbles form as the water boils in this video.

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