Vaporization is the process by which liquid molecules go into the gas state. So it's going from here to here. Once again, just like the change in enthalpy of fusion, change in enthalpy of vaporization is also positive. It's endothermic because we take a large number and we subtract a small number from the large number and we get a positive number. And once again, going from this stage to this stage, or from a gas to a liquid, which is called condensation, well, that's exothermic. That's negative, because we take this number, subtracted from this number, and we get a negative number.