With places loaded into a geofencing service, you can build Smartphone apps to trigger when a user enters or leaves the static area that you care about. Your app could send an email, text or multimedia alert to the user (“Billy has arrived safely at school!”) or trigger an action such as updating a database. Imagine a geofence that automatically checks you in to one of your favorite venues, without having to even interact with the Foursquare mobile client. Or when you leave, it checks you out so your friends aren’t wondering where you are.