A trespassing or perimeter alarm system detects unauthorized entry or intrusion into a specific area, such as your home, commercial building, or restricted zone.
Arming your alarm system and determining when to set it largely depends on your preferences, lifestyle, and the level of security you feel you need for your home.
There are various devices used in home security systems to detect intruders and trigger a burglar alarm, such as door and window, motion, and other hardware.