Water is a gas when it's in the form of water vapor. This happens when water molecules gain enough energy to break free from their liquid state and become individual molecules in the air. Here's a breakdown:

* Liquid water: Water molecules are close together, attracted to each other.

* Water vapor: Water molecules have enough energy to move freely, not bound to other water molecules.

Here are some ways water becomes a gas:

* Boiling: When water reaches its boiling point (100°C or 212°F), it rapidly changes into water vapor.

* Evaporation: Water molecules at the surface of a liquid gain enough energy to escape into the air, even at temperatures below the boiling point. This happens more quickly when it's hot or windy.

* Sublimation: In very cold conditions, ice can directly change into water vapor without going through the liquid phase.

So, while we don't usually see water in its gaseous form, it's present in the air all around us!