A fire extinguisher is an active fire protection device used to extinguish or control small fires, often in emergency situations. It is not intended for use on an out-of- control fire, such as one which has reached the ceiling, endangers the user (i.e.,no escape route, smoke, explosion hazard, etc.), or otherwise requires the expertise of a fire brigade.
Typically, a fire extinguisher consists of a hand-held cylindrical pressure vessel containing an agent which can be discharged to extinguish a fire. Fire extinguishers manufactured with non-cylindrical pressure vessels also exist but are less common.