Car alarm

Car alarm siren

A car alarm is an electronic device installed in a vehicle in an attempt to discourage theft of the vehicle itself, its contents, or both. Caralarms work by emitting high-volume sound(usually a siren, klaxon, pre-recorded verbal warning, the vehicle's own horn, or a combination thereof) when the conditions necessary for triggering are met, as well as by flashing some of the vehicle's lights, and (optionally) notifying the car's owner via a paging system and interrupting various electrical circuits necessary for the car to start.

An early version of a car alarm for use as a theft deterrent was invented by an unknown prisoner from Denver in 1913.^[1] This version was manually armed, and triggered when someone tried to crank the engine. A later alarm inspired by an early version of a remote starter was published in 1916.^[2] This version had the car owner carry a receiver, which would buzz if the car ignition system was tampered with.