system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why metal gets glowing red when it's extremely hot ?

Title says it all, also, some elements that aren't metal like salts get glowing red.
gpt
Everything is emitting light all the time.  Most objects around us are cold, and only emit very low energy infrared light that we can't see but can sometimes feel as heat.

When objects get hotter, they start emitting higher energy light.  When they get hot enough they start emitting visible light, starting in the dull red and moving towards white and eventually vivid blue as they reach thousands of degrees.

The color of the light is directly related to the surface temperature of the material, and this is called "blackbody" radiation.  It doesn't matter if it's molten metal, a ceramic plate, or the churning surface of a star, they all emit the same light at the same temperature.