Geofencing uses mobile device location to target ads and messages to customers. When customers are near a store, ads can remind them of purchases or offer discounts. As customers leave, ads can encourage return visits or online shopping. Geofencing displays ads on many websites and apps to build brand awareness cost effectively. Ads target audiences based on location, interests, and prior website visits. Optimization shifts budgets to most effective ad placements and networks to boost conversions. Geofencing provides real-time tracking of ad performance and marketing ROI.