How do they make light?

Answer

You can make light in many different ways. The oldest way is via a “light bulb”: you run an electric current through a finely coiled metal wire, and that wire gets so hot that it starts to glow and gives off light. You probably also know the “TL lamp” or “energy saving lamp”; it works because the electrical voltage across the lamp causes electrons to store energy and release it back, and light is released during this release.

You can find some more details on wikipedia: http://nl.wikipedia.org/wiki/Lamp.