A fluorescent light or tube is a lamp or bulb discharged with gas, namely mercury vapour. When electricity is introduced the atoms in the mercury produce shortwave ultraviolet light that in turn causes a phosphor to “fluoresce” producing a bright light. A fluorescent form of lighting converts electrical power into a more efficient use of electricity than a normal incandescent light. Although the initial cost of the appliance is greater than a normal lighting system, the running costs are much lower. The high cost of the light is mainly due to it requiring a “ballast” to regulate current flow. In the past this type of lighting was used mainly in the commercial sector like offices and factories but these days the everyday compact fluorescent lamp is now available in the same popular specifications as the normal bulbs, and can come in various energy saving options.