system
Given the following post, respond as if you're commenting on Reddit:
human
Why does fire produce light?
gpt
Everything above absolute zero emits electromagnetic radiation. The more energetic (hotter) something gets, the more radiation it emits both in total and in more areas of the spectrum.

Visible light is electromagnetic radiation that falls in a narrow part of the spectrum that our eyes can detect. There's also ultraviolet, infra-red, radio, etc...

Stuff that's burning is usually so energetic that it emits enough radiation in the right parts of the spectrum for your eyes to see it clearly, especially at night when everything else in the surroundings is just emitting tiny amounts of (invisible to us) IR.