Geofencing

Geofencing is the practice of defining a virtual boundary, usually a circle around a point or a custom polygon, around a real-world location, and detecting when a mobile device enters, exits or dwells inside it. The boundary is drawn in a geographic information system and evaluated against a device's GPS, Wi-Fi or cell-tower location signal.

Detection accuracy depends on the location technology used: GPS gives tighter boundaries outdoors but drains battery and struggles indoors, while Wi-Fi and cell-tower triangulation are coarser but more power-efficient, which is why many apps combine methods and add a dwell-time threshold to avoid firing on a brief pass-by. This differs from simple geocoding-based proximity, which checks distance to a single point rather than true containment inside an arbitrary boundary shape.

Marketers use geofencing to trigger location-based notifications or attribute a store visit to an ad exposure, feeding footfall analytics and broader spatial analysis of visit patterns; logistics and security uses include alerting when a vehicle or asset leaves an approved zone. The main pitfalls are location-signal noise causing false entry or exit events near a boundary edge, and privacy and consent obligations, since continuous location tracking is personal data under most privacy regulation.