The light sources available to us today differ from one another, depending on where they are used, their structural design and such properties as light colour and light quantity. However, the principle of illumination on the atomic or molecular levels is similar for all. For example the light bulb, still the most used source of light in homes, produces light by heating a Wolfram wire - i.e. the same thermal method as the sun. On the other hand, a light stick is illuminated by a chemical reaction that is triggered by mixing two liquids together when the stick is bent. Deep sea divers, for example, use such lamps underwater, where creating electricity or warmth presents a problem.

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