pay-per-action -or- pay per action, a.k.a. promoted updates
An online advertising model similar to search ads. Also known as "promoted updates" 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 such as Foursquare.
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.