Geofencing is a technology that creates a virtual boundary around a specific geographic area. It uses GPS, RFID, Wi-Fi, or cellular data to define this area, allowing businesses and applications to trigger actions when a device enters or exits the designated zone. This can include sending notifications, alerts, or advertisements to users' smartphones. Businesses often use geofencing for targeted marketing, enhancing customer engagement, and improving location-based services. For example, a retail store might send a special offer to customers' phones when they walk near the store, encouraging them to visit and make a purchase.