By generating more direct bookings, TripAdvisor and Yelp can potentially boost advertising revenue by keeping their visitors on their sites for longer periods. And while transactional revenue remains far less than click-based advertising revenue for TripAdvisor (Yelp doesn't break out its revenue sources), TripAdvisor's Q2 subscription, transaction and "other" revenue surged 55% from a year earlier, outpacing the company's overall 15% revenue gain. Both companies began stepping up their transactional options earlier this year. Trip-Advisor, which was spun off by Expedia in late 2011, went live with its Instant Booking feature in June with inventory from Choice Hotels International, hotel-booking site and TripAdvisor's discount hotel-booking OTA, Tingo. Get the full story at Travel Weekly Read also "Expedia expects to get pressured by TripAdvisor, its largest search partner" at Skift