After the introduction of Google Maps in 2005 and smartphones in 2007, online local marketing began to rapidly expand. Google Maps on desktop computers enabled the targeting of ads to users based on a general sense of their IP address and enabled merchants to display ads to users based on the general location of potential customers, usually within a several square-mile radius. IP addresses can be used to identify a city, and a neighborhood within the city, but not a zip code, street, or building. Google Maps helped users answer the question “Where can I find an Italian restaurant” in a city or section of a city from their desktop. The arrival of smartphones in 2007, and Google’s mobile maps app, took this one step further. The GPS receivers in second-generation smartphones introduced in 2008 (Apple’s 3G iPhone), along with other techniques, meant that a user’s location (latitude and longitude) could be fairly well known by cell phone manufacturers, marketers, service providers, and carriers like AT&T and Verizon. These developments opened an entirely new growth path for local online advertising that heretofore had been confined to the desktop. In this new world, a local food market could shout out to mobile phone users as they walked by the store, offering discounts to responders, and users in turn could search for specific retail stores nearby, even checking their inventory before walking into the store.