It all starts with a human, though. And most likely, the human starts on TripAdvisor. The popular site, which was bought by Internet conglomerate IAC in 2004 and spun off as part of Expedia, gets more than 32 million visits a month—six times the number of hotel rooms in the U.S.—and generates annual revenue of $350 million.
TripAdvisor relies on the volunteer efforts of travelers who relate their experiences at various hotels, much as restaurant diners do for Zagat or music listeners do for Amazon. The company launched in 2000 as an Internet search engine that pulled travel information from existing sources, including message boards, guidebooks, and magazines. At first, users added comments about hotels as a means to emote, not with any idea that they were contributing to the construction of a database. “We were actually a little nervous about whether the site would just turn into a gripe site,” says cofounder and CEO Stephen Kaufer.