Now let's go to the first definition. Now let's remember what heat is. Heat is a transfer of energy from a cold body to a hot body, which means that an energy transfer only occurs when there is a difference in temperature. So one way to define temperature is to say that temperature is a property of matter that determines if energy transfer can occur. That is, if there is no difference in temperature. If the temperature of one object and a second object are the same, no energy transfer due to heat can occur.