Geofencing is a location-based service that allows you to set up a virtual perimeter around a real-world location. When you enter or leave the defined area, your device will receive a notification. Geofencing can be used to track your movements, and to send you targeted ads and special offers based on your location.
To protect yourself from geofencing, you can turn off location services on your device, or opt out of location-based ads and services. You can also install a geofencing blocker, such as PrivacyFix, which will prevent companies from collecting your location data.