The self-emission of radiant energy in the visible spectrum due to the thermal excitation of atoms or molecules.
The emission of light by thermal radiation of a temperature high enough to render the source of radiation visible.
The emission of light by raising the material to a high temperature.
Incandescence is the release of thermal radiation from a body due to its temperature. The release of radiation is usually in the infrared and visible regions of the electromagnetic spectrum. Incandescence occurs in light bulbs, because the filament resists the flow of electrons.