What is fire? Fire is hot but where does it come from? Fire is the result of extreme heat, usually when organic chemicals combusted with oxygen(thank you chemistry) but where does the light come from? The light results from electrons absorbing the heat energy and jumping up energy levels like we learned last year and the light is produced when the electrons fall back down to their ground state. However fire can look different. The fire from Bunsen burners in chem or propane fires look a lot different that wood fires. The propane fires burn cleanly and they give off blue light. However wood fires don't burn cleanly and there is some blue light but soot and other particles that are burning red hot give off the red glow.