Oxygen,
heat, and fuel are frequently referred to as the "fire triangle." Add in the
fourth element, the chemical reaction, and you actually have a fire
"tetrahedron." The important thing to remember is: take any of these four
things away, and you will not have a fire or the fire will be extinguished.
Essentially,
fire extinguishers put out fire by taking away one or more elements of the fire
triangle/tetrahedron.
Fire
safety, at its most basic, is based upon the principle of keeping fuel sources and
ignition sources separate.