PPA

An online advertising model similar to search ads. PPA ads operate like Google's promoted listings or Twitter's promoted tweets. They are pay-per-action ad placements that only appear when a user is searching for a venue using a check in site.

Pay per action models exist on location-based social networking sites such as Foursquare because the technology can determine a user's current location and check-in history before displaying a promoted update. The ads are powered by a recommendation engine and include a store's recent news, photos or specials.