The first time I heard the term microfencing I pictured a miniature John Carter sword fighting aliens on the moons of Mars.

A sign of a misspent youth reading sword-and-planet stories.

For microfencing is actually just a more precise form of geofencing. In geofencing, you set an alert in an app that a customer or panelist has downloaded to notify you whenever the user is within specific GPS coordinates. Those GPS coordinates might be every Wal-Mart in the country, every Starbucks in a state, or a specific Dunkin’ Donuts in Des Moines. You can pop up a coupon or a survey when a user enters or exits the geofence, or you can just log their presence for action later. For instance, ResearchNow shared a great case study about passively logging visits to automotive dealers to update their profile data on which panelists were potentially shopping for cars.

Read more at Green Book