Glossary A–ZLetter G
Geofencing
Geofencing places a virtual fence around a location and triggers an action when a device enters or leaves that area.
The fence is defined by coordinates and a radius or by an area on the map. The location usually comes from mobile phones.
Around screen networks there are two uses. First, advertisers can later target phones that were near a screen with further advertising on the phone. Second, effectiveness studies use geofences around screens and shops to count how many phones were registered first at the screen and then in the shop. An example: a fence of 100 metres around a screen and another around the nearest branch.
Geofencing is only as accurate as the devices' location, and that varies considerably. A fence that is too large captures people who never saw the screen. The method also relies on location data from phones, which requires a sound legal basis, usually consent within the app concerned. When looking at studies, operators should ask about fence size, data source and the comparison used. Geofencing differs from geotargeting in that it is tied to entering an area.