Incandescence

Incandescence is the release of electromagnetic radiation from a hot body due to its high temperature. The release of radiation is usually in the infrared (heat) region, known as thermal radiation, and the visible light region of the electromagnetic spectrum. Incandescence occurs in light bulbs, because the filament resists electron flow. This excites electrons in the filament material to jump to a higher orbit, and thus subsequently release a photon. The same process occurs when something is on fire or during an explosive or a combustion reaction. Incandescence can also produce X-rays, but usually most of the energy is dissipated in the form of infrared radiation.