In physical science, freezing or solidification's the process in which a liquid turns into a solid when cold enough. The freezing point's the temperature at which this happens. Melting, the process of turning a solid to a liquid,'s almost the exact opposite of freezing. All known liquids undergo freezing when the temperature's lowered enough, with the sole exception of liquid helium, which remains liquid at absolute zero and can only be solidified under pressure. For most substances, the melting… (More on Freezing)