A security alarm is a system designed to detect intrusion – unauthorized entry – into a building or area. Security alarms are used in residential, retail, commercial and industrial properties for protection against burglary (theft) or property damage, as well as personal protection against intruders.
Some alarm systems serve a single purpose of burglary protection; combination systems provide both fire and intrusion protection. Intrusion alarm systems may also be combined with closed-circuit television surveillance systems to automatically record the activities of intruders, and may interface to access control systems for electrically locked doors. The use of an alarm monitoring service providers, offers additional protection by a means of alerting others who can help and assist in protection against property damage or personal harm. Systems range from small, self-contained noisemakers, to complicated, multi-area systems with computer monitoring and control. These systems can be wired or wireless systems.