What is geofencing? Provide an example

What will be an ideal response?

The idea of geofencing is to target customers with a mobile promotion when they are within a defined geographical space, typically near or in a store. The local-based service requires just an app and GPS coordinates, but consumers have to opt in. Cosmetics retailer Kiehl's uses geofencing around its free-standing stores and kiosks within other stores. Students may know other examples.