A Fire extinguisher, or 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 require the expertise of a fire department. Typically, a fire extinguisher consist 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 exit, but are less common.

All fire extinguishers must be painted signal red. Except for water extinguishers, each extinguisher has a coloured band near the top, covering at least 10% of the extinguisher's body length, specifying its contents.

The types of fires and additional standards are described in NFPA 10: Standard for Portable Fire Extinguishers, 2013 edition.