Intruder alarms are security solutions that guard against unauthorised entry into a building, at least, curatively. It detects such entry into a building through the use of sensors linked to places of entry like doors, windows, and even skylights. When these sensors are triggered under certain conditions, a signal is sent to the alarm, which then alerts the ARC (alarm receiving centre) and the keyholders of the building. They may sometimes come with extra security features like panic buttons and break glass detectors.