What state of matter is fire?

According to the US Department of Energy, fire is not a state of matter but is a form of energy. Fire is a combination of heat and light energy with small amounts of sound.

There are four different states of matter which include solid, liquid, gas and plasma. Solids, including steel and dry ice, have a very distinct shape and volume, while liquids, like oil and water, take the shape of their containers. A gas does not have a definite shape or volume. Examples of gases include air and oxygen. Plasma, including stars, also does not have a definite volume or shape, but it does possess unique properties.