Blackbody
Definition
An idealized perfect absorber and emitter of radiation — the theoretical standard for how hot objects glow.
Technical definition
An object absorbing all incident electromagnetic radiation and emitting with the maximum possible spectrum at its temperature (Planck's law). Its total emission follows the Stefan-Boltzmann law (∝ T⁴); peak wavelength follows Wien's displacement law (λ_max ∝ 1/T).
Example
The Sun (~5800 K) approximates a blackbody peaking in visible light; a human body (~310 K) peaks in the infrared — which is why thermal cameras see us glow.
Common confusion
‘Black’ does not mean black-colored — it means perfectly absorbing. A blackbody at 5800 K glows white-hot. The name refers to ideal absorption, not appearance.