Temperature is mostly responsible for the form of matter. For instance, when raising the temperature you're adding energy. This energy gives the individual molecules and atoms the ability to overcome the forces that hold them together. This can be seen when a solid turns into a liquid or a liquid turns into a gas. However, when you're lowering the temperature you're removing energy. The lack of energy results in less movement from the atoms. Gases condense into liquid because the atoms don't have enough energy to stay away from each other. Liquids solidify because the atoms don't have enough energy to slide past each other and they get stuck in place. So in conclusion, temperature determines how how much energy atoms have that allow them to move at different speeds which determines the state of matter.