An alarm system is a set of devices, equipment and software designed to detect unauthorized access or intrusion into a building or area, sounding an alert to deter or notify authorities. It typically includes sensors, alarms, and communication systems that work together to provide security against burglary, fire, smoke, carbon monoxide poisoning, and other potential hazards. The purpose of an alarm system is to protect property and prevent harm by providing early warning and rapid response in case of emergency.