Matter is defined as anything that has mass and takes up space (volume). Matter exists in three physical states:
*Liquids and gases are called fluids
The three states respond differently to changes in temperature and pressure. They increase in volume with an increase in temperature. The effect is much bigger for a gas. The volume of a gas at a fixed temperature can easily be reduced by increasing the pressure because they are compressible. Liquids are slightly compressible and solids are not.