Portable fire extinguishers apply an extinguishing agent that will either cool burning fuel, displace or remove oxygen or stop the chemical reaction so a fire cannot continue to burn.

When a handle on a fire extinguisher is compressed, it opens an inner cannister of high-pressure gas that forces the extinguishing agent from the main cylinder through a siphon tube and out the nozzle.

A fire extinguisher works much like a can of hair spray.