A Smoke Detector is a device that detects smoke. Commercial, industrial, and mass residential devices issue a signal to an alarm system, while household detectors, known as smoke alarms, generally issue a local audible and/or visual alarm from the detector itself. Most smoke detectors work either by optical detection (photoelectric) or by physical process (ionization), while others use both detection methods to increase sensitivity to smoke.

Having these monitored devices installed may give the user a reduced rate from their insurance company.