Traveler review sites—led by TripAdvisor—created and drove the growth of the traveler hotel review category, demonstrating the potential role of user-generated reviews in the trip-planning process. The travel industry took notice. Expedia acquired TripAdvisor, Travelocity picked up IgoUgo, Priceline stepped in with MyTravelGuide, and SideStep bought TravelPost (which in turn was acquired by Kayak and recently sold to a startup led by Expedia´s original founders).
But in 2009 something very interesting happened: travelers posted far more reviews on OTAs than on traveler review sites—nearly three times as many. Travelers posted more than 700,000 reviews across the six largest OTAs in 2009, versus less than 250,000 on traveler review sites (see Figure 1).