When water changes from a liquid state to a solid state, the process is called solidification (freezing), this change in matter strengthens the intermolecular forces of the molecules and is hence an exothermic reaction, which releases energy.
When water changes from a liquid state to gaseous state, the process is called evaporation (vaporization), this change in matter weakens the intermolecular forces of the molecules and is hence an endothermic reaction, which absorbs (uses) energy
