A fire extinguisher is a portable device designed to put out small fires. It contains a fire-suppressing agent, which can be released by pulling a pin and squeezing a handle. Fire extinguishers are classified into different types based on the kind of fire they are effective against, such as Class A for ordinary combustibles, Class B for flammable liquids, and Class C for electrical fires. Using a fire extinguisher requires knowledge of the PASS technique: Pull the pin, Aim the nozzle, Squeeze the handle, and Sweep the base of the fire. Regular maintenance and inspections are essential to ensure that fire extinguishers are functional and ready for use in emergencies.