A fire extinguisher is an active fire protection evice used to extinguish or control small fires, often in emergency situations. It is not designed for use on an out-of-control fire, such as one which reaches the ceiling, endangers the user (i.e. no escape route), or otherwise requires the expertise of a fire department. Typically, a fire extinguisher consists of a handheld cylindrical pressure vessel containing an agent which can be discharged to extinguish a fire.