A matter can exist in three different forms: solid, liquid, or gas.

Solid is a state of matter in which particles are closely packed and held together by strong forces, giving it a definite shape and volume. Examples of solids include ice, wood, and metal.

Liquid is a state of matter in which particles are close together but can move freely, giving it a definite volume but no definite shape. Liquids take on the shape of their container. Examples of liquids include water, oil, and mercury.

Gas is a state of matter in which particles are widely spaced and move freely, giving it neither a definite shape nor a definite volume. Gases take on both the shape and volume of their container. Examples of gases include air, oxygen, and helium.

Other states of matter, such as plasma and Bose-Einstein condensates, also exist under specific conditions.