Black-body radiation is the thermal electromagnetic radiation within, or surrounding, a body in thermodynamic equilibrium with its environment, emitted by a black body. A black body is an idealized object that absorbs all electromagnetic radiation it comes in contact with and then emits thermal radiation in a continuous spectrum according to its temperature. The radiation emitted by a black body has a characteristic, continuous frequency spectrum that depends only on the bodys temperature, called the Planck spectrum or Plancks law. The spectrum is peaked at a characteristic frequency that shifts to higher frequencies with increasing temperature, and at room temperature, most of the emission is in the infrared region of the electromagnetic spectrum.

All objects emit electromagnetic radiation according to their temperature. Colder objects emit waves with very low frequency (such as radio or microwaves), while hot objects emit visible light or even ultraviolet and higher frequencies. The spectral intensity of black-body radiation peaks at a frequency that increases with the temperature of the emitting body. Factors that affect the amount of radiation of a particular wavelength given off from a surface include the type of material absorbing the incident radiation and the temperature of the surface.

The concept of black-body radiation is seen in many different places. For example, the intensity of the energy coming from a radiator is a function only of temperature/Quantum_Mechanics/01._Waves_and_Particles/Blackbody_Radiation). A good example of this temperature dependence is a flame. The flame starts out with a low frequency emitting red light in the visible range, as the temperature increases, the flame turns white and then blue as it moves across the visible spectrum with an increasing temperature/Quantum_Mechanics/01._Waves_and_Particles/Blackbody_Radiation).

In summary, black-body radiation is the thermal electromagnetic radiation emitted by a black body, which is an idealized object that absorbs all electromagnetic radiation it comes in contact with and then emits thermal radiation in a continuous spectrum according to its temperature. The radiation emitted by a black body has a characteristic, continuous frequency spectrum that depends only on the bodys temperature, called the Planck spectrum or Plancks law.