Blackbody radiation

Blackbody radiation is radiation produced by heated objects, particularly from a blackbody. A blackbody is an object that absorbs all radiation (visible light, infrared light, ultraviolet light, etc.) that falls on it. This also means that it will also radiate at all frequencies that heat energy produces in it.

Everything glows, depending on its temperature. Hotter things glow more in shorter wavelengths. Cooler things don't glow so much, especially in short wavelengths. Partly the radiation wavelength depends on what the material is, and partly it doesn't. The part that only depends on temperature, and not on composition, is called blackbody radiation.