This is the Fire Triangle. Actually it's a tetrahedron, because there are four elements that must be present for a fire to exist. There must be Oxygen to sustain combustion, Heat to raise the material to its ignition temperature, Fuel to support the combustion and a Chemical Reaction between the other three elements.
The concept of Fire Prevention is based upon keeping these four elements separate.
Click any of the 4 Elements to extinguish the fire.