An object that absorbs all radiation falling on it, at all wavelengths, is called a black body.
- A black body is an idealized physical body that absorbs all incident electromagnetic radiation, regardless of frequency or angle of incidence.
- When a black body (at a uniform temperature), emits radiation (visible light, infrared light, ultraviolet light, etc.), the frequency distribution depends on its temperature.
- The emitted radiation is called black-body radiation.