Fire is a very rapid chemical reaction between oxygen and a combustible material, which results in the release of heat, light, flames, and smoke.
The Fire Triangle
For a reaction that creates a fire, the following three elements, which are represented by the three sides of the Fire Triangle, must be present at the same time:
The Fire Tetrahedron
The Fire Tetrahedron introduces a fourth component – the uninhibited chain reaction – to the fire triangle. This representation more accurately describes the fire as a chain reaction process. The chain reaction acts as a feedback loop mechanism of heat to produce the gaseous fuel used in the flame. This feedback provides the heat necessary to maintain the fire. The fuel, oxygen and heat join together in a sustained chemical reaction.