Heat is a form of energy that cannot be seen but can be felt in matter. Most sources of light are also sources of heat. The Sun is our main source of heat energy. Heat is the amount of energy in a matter that makes it feel hot or cold. Heat moves from a hot matter to a cold matter when they are in contact. Any matter, whether hot or cold has certain amounts of heat. A hot matter has more amount of heat than a cold matter. Molecules in a matter are in a constant movement. The faster the molecules move, the more heat energy they have and the hotter the matter becomes. If we drink a hot cup of coffee, our body gains some of the heat and we feel warmer. Molecules in a cold drink on the other hand move very slowly because they have a very small amount of heat. When you drink it, it takes away some of the heat from your body, thus makes you feel cooler. When a substances gains heat, it becomes warmer and the temperature increases. When it loses heat, it becomes cooler and the temperature decreases. We can use our sense of touch to tell whether one substance is warmer or cooler that the other. However, it does not indicate the difference in hotness of matter accurately.