http://www.newsweek.com/injury-law-firms-are-force-feeding-er-patients-mobile-ads-948707

Patients who visit emergency rooms in Philadelphia are being targeted with ads for injury law firms.

According to National Public Radio, the law firms are using technology known as geofencing. Often used to share discounts and offers from shops, geofencing connects to your phone once a person has entered a certain area—in this case, a hospital. It works by locating a phone using Wi-Fi, cellular data and GPS.