ABC powder is a type of fire extinguisher agent that is effective against three classes of fires: Class A (ordinary combustibles like wood and paper), Class B (flammable liquids), and Class C (gases). It is made from a mixture of ammonium phosphate, ammonium sulfate, and other additives, which help to smother flames and interrupt the chemical reaction of fire. This versatile powder is commonly used in portable fire extinguishers and is recognized for its ability to quickly suppress fires. However, it can be corrosive to certain materials, so care should be taken when using it in sensitive environments.