Motion sensors trigger an alarm when they detect motion within the home. That being said, because motion sensors can be fooled and often don’t cover the entire area of a room, it’s not a good idea to base your entire security system on motion detectors. While you might be inclined to think that a motion sensor system is off the table if you have a pet, many models have a pet-immune mode that will ignore movements from animals under a particular weight or size while still going off when a full-size human enters the home.
