Blackbody

A black body is an idealized physical body that absorbs all incident electromagnetic radiation regardless of frequency (and wavelength).

A black body in thermal equilibrium has a few notable properties
 * 1) It is an ideal emitter
 * 2) It is a diffuse emitter, the energy is radiated isotropically, independent of direction
 * 3) It emits as much energy as it absorbs

Flux at the Surface
This equation can also be found in flux but will be included here for good measure. The flux emitted at the surface of a black body is described with:

$$F _{blackbody, surface} = \sigma T^4$$