Out Of Nowhere, TripAdvisor Becomes One of Facebook's Biggest Apps

Over June, the Facebook app of travel reviews site TripAdvisor has increased its Monthly Active Users (MAU) by over 67 percent. It now has 31 million MAU, moving it up to fourth on AppData's Facebook Apps Leaderboard - just above the ever-popular MyCalendar birthday app and Zynga's top 'Ville game CityVille. What makes it even more intriguing is that in May, according to InsideFacebook (a sister site of AppData), TripAdvisor experienced "a steady decline." So how has TripAdvisor not only stopped a decline, but added 12.5 million users in the space of a month?

The growth has been particularly rapid this past week. According to AppData, TripAdvisor's Facebook app was the top gainer across Facebook last week with 6.2 million new MAU. That's a 25% gain in just one week.

TripAdvisor is one of my favorite travel websites. I use it to choose hotels, before I travel. That's because it has a vast database of user-generated hotel reviews and its ranking system is slick and dependable. Also, unlike Orbitz, TripAdvisor doesn't penalize me for using a Mac.

TripAdvisor released its first Facebook app back in June 2007, called "Cities I’ve Visited." This is the very same app that now attracts 31 million monthly active users, although now it's simply called TripAdvisor (a separate app called Cities I've Visited still shows up in Facebook's search, but it re-directs to the TripAdvisor app). TripAdvisor integrates onto your Facebook Timeline and automatically shares your activity.

Is the user growth related to TripAdvisor's "Instant Personalization" feature, which it introduced in 2010 as an official partner of Facebook? Instant Personalization means that TripAdvisor uses Facebook data that you've made public - such as your name, profile picture, gender and networks - to serve you a personalized experience. The key is it doesn't require your permission to do this. Even if you don't have a TripAdvisor account, if you are logged into Facebook then you will see reviews from your friends and other "personalized" information on TripAdvisor.com. There are seven other companies in the Instant Personalization program, including local reviews site Yelp and Microsoft's Bing search engine.

While this shows that TripAdvisor is a close partner of Facebook, Instant Personalization doesn't explain the sudden ramp up of TripAdvisor's Facebook app. Neither does a new app it released last week, called Local Picks. That app, which provides dining recommendations, is TripAdvisor's second on Facebook. But it's a separate app and so it doesn't impact the statistics of the TripAdvisor Facebook app.

So what is (literally) up with TripAdvisor's Facebook app? InsideFacebook suggests it is "due in part to a Facebook Sponsored Stories campaign to re-engage users." In other words, TripAdvisor has been advertising on Facebook. If this is the main reason for TripAdvisor's jump on Facebook, then it must be considered an amazing return on investment!

It may also be that it's summer in the U.S. and Europe, so people are using TripAdvisor more and socializing their travel on its Facebook app.

We're going to have to appeal to the wisdom of the crowds on this one. Let us know in the comments what you think has caused TripAdvisor to suddenly become one of the most popular apps on Facebook!