Fire extinguisher, portable or movable apparatus used to put out a small fire by directing onto it a substance that cools the burning material, deprives the flame of oxygen, or interferes with the chemical reactions occurring in the flame.Fire extinguishers are classified by the type of fires they are designed to extinguish. There are five basic classifications of fuel:A,B,C,D,K, and they are labeled with either letter-shaped or pictorial symbols that indicate what types of fires are intended for.Fire extinguishers are divided into handheld and cart-mounted (also called wheeled extinguishers).Like any mechanical device, fire extinguishers must be maintained on a regular basis to ensure their proper operation.