What is a good scientific explanition of the substance known as fire?

shantaram

FIRE:Rapid burning of combustible material with the evolution of heat and usually accompanied by flame. It is one of the human race's essential tools, control of which helped start it on the path toward civilization. ---encyclopaedia britannica online Feb 18 02, 1:52 AM

Barrow boy

As I interpret it, the thing we associate with fire is flame, and the question is in effect asking what flames are. Flame is also an element of the previous answer. Flames, I think, are the observable radiation given off by superheated gases or microparticles (as in a candle flame). Once these gases etc lift clear of the fire they cool rapidly and the radiation is undetectable to the human eye. That is why flames have a finite height. Feb 18 02, 8:19 AM

Gnomon

Fire is a runaway chemical reaction in which the thing which is burning combines with oxygen in the atmosphere to make a new compound, usually producing water vapour in the process. This chemical reaction gives off heat. The heat causes gases to come out of the burning substance, which burn and give off heat and light. The shell of gas around the burning item is called flame. Feb 18 02, 5:40 PM