Incandescence

Incandescence is the release of electromagnetic radiation from a hot body due to its high temperature. The release of radiation is usually the infrared (heat) and visible light areas of the electromagnetic spectrum. Incandescence occurs in both light bulbs where the electrical resistance to electron flow excites electrons in the material to jump to a higher orbit, and thus subsequently release a photon; and when something is on fire or during an explosive or a combustion reaction. X-rays can also be produced by incandescence, but often most energy is wasted in the form of heat.