Fire extinguishers come in various classes including A, B, C, and D, and are rated as to what types of fires they are meant to extinguish. -Class A extinguishers are designed to fight traditional types of combustible materials such as wood and paper products. They are sized by the amount of liquid they hold. Type A=things that make Ashes. -Class B extinguishers are designed to fight fires of combustible liquids such as gasoline, grease, or kerosene. They are sized by the number of square feet of fire they can extinguish. Type B=things that Boil (liquids). -Class C extinguishers are designed to fight fires of an electrical nature such as wiring, breakers, and outlets. These types of fires pose an electrocution hazard, so the extinguisher must produce a substance that is non-conductive. Type C=Current Carrying. -Class D extinguishers are designed to fight chemical fires found in a laboratory. Some extinguishers have multiple ratings such as an ABC type extinguisher.