Electricity is actually made up of extremely tiny particles, called electrons, that you cannot see with the naked eye unless you have been drinking. Electrons travel at the speed of light, which in most American homes is 110 volts per hour. This is very fast. In the time it has taken you to read this sentence so far, an electron could have traveled all the way from San Francisco to Hackensack, New Jersey, although God alone knows why it would want to. The five main kinds of electricity are alternating current, direct current, lightning, static, and European. Most American homes have alternating current, which means that the electricity goes in one direction for a while, then goes in the other direction. This prevents harmful electron buildup in the wires.Dave Barry, "The Taming of the Screw"