What does a home alarm system do?

A home alarm combines three jobs. It detects — using contact sensors on doors and windows, PIR motion sensors in rooms, and sometimes glass-break or vibration detectors. It deters — a loud siren is the single most effective element, because most intruders leave the moment one sounds. And it alerts — sending you an instant notification (and, on some systems, calling a monitoring centre) so you can respond, call for help, or check your cameras. A basic system is a hub, a few sensors and a siren; you add sensors and panic buttons to suit your home.