Energy-saving lights need no more than one-fifth of the energy consumed by an incandescent light bulb. This is due to the different methods by which the light produced. An incandescent bulb heats up its wire coil to give off light. However, it only transforms 4% of the electricity into light, and the remainder is released as heat, resulting in a huge waste of energy. Energy-saving lights, regardless of their shape, are in fact fluorescent lamps in which gas molecules emit ultraviolet light, which causes the inner coating of the lamps to glow. The bulb stays cool because less energy is required. However, the future is likely to belong to light-emitting diodes. They are very bright, but they consume only one-tenth of the energy used by incandescent light bulbs.