1. Solid - Matter in a solid state has a fixed shape and volume, and its particles are tightly packed together. Solids can only change shape if they are broken or melted.

2. Liquid - Matter in a liquid state has a definite volume but no fixed shape. Liquids take the shape of their containers, and their particles are close together but not as tightly packed as they are in solids.

3. Gas - Matter in a gas state has neither a fixed shape nor a fixed volume. Gases expand to fill their containers, and their particles are far apart and move freely.