What are the three essential requirements to produce fire? How fire extinguisher is useful for controlling the fire.

The three essential requirements to produce fire are:

1) Fuel,

2) Air (Oxygen),

3) Heat for reaching the ignition temperature.

A fire extinguisher is used for extinguishing fires that are related to electrical appliances or petrol. It cuts off the supply of air to bring down the temperature of the fuel or both.