Geo-fencing is a feature that uses the GPS (global positioning system) or RFID (radio frequency identification) to define geographical boundaries.
Geo-fencing allows home builders to set up triggers that issue an alert (ad) when a device enters (or exits) the defined boundaries. Many geo-fencing applications incorporate Google Earth, allowing the builder to define boundaries on top of a satellite view of a specific geographical area. Other applications define boundaries by longitude and latitude or through user-created maps.
Geofence virtual barriers can be active or passive. Active geofences require an end user to opt-in to location services and a mobile app to be open. Passive geofences are always on; they rely on Wi-Fi and cellular data instead of GPS or RFID and work in the background.