system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:What is Black Body Radiation?
gpt
A black body is an idealized perfect absorber of electromagnetic radiation. All of it, regardless of angle or wavelength. Including your wifi signal. Given that it doesn't reflect or scatter *any* of it, we call them black. What does it do with the radiation it has absorbed? It gets warm. 

Each object emits infrared radiation according to its temperature. You are emitting right now at almost 37°C. 

A black body has absorbed all radiation, is in thermal equilibrium, has increased its temperature. What is the only thing it can do now? re-emit the absorbed radiation as infrared thermal radiation. Heat. That's black body radiation.