system
Given the following post, respond as if you're commenting on Reddit:
human
What is fire?

Essentially, is it a kind of plasma?  Is it pure energy?  What?
gpt
It's a reaction between oxygen and a fuel (usually a hydrocarbon or related compound) producing carbon dioxide and soot. The reaction is really hot so the products start to emit blackbody radiation, and also rises because hotter gas is less dense.