According to the United Nations tourism organization, there were more than one billion international trips taken during 2012 alone. In a new book titled, Overbooked: The Exploding Business of Travel and Tourism , journalist Elizabeth Becker traces the history of tourism and points to the challenges facing the fast-growing industry, which currently contributes .5 trillion to the world’s economy. In this interview with Knowledge at Wharton, Becker discusses the role that both individuals and countries must play as the tourism industry undergoes significant change. An edited transcript of the conversation follows. Knowledge at Wharton: We are here today with Elizabeth Becker, author of Overbooked: The Exploding Business of Travel and Tourism . Elizabeth, thanks for speaking with us. You spent five years working on this book, including several trips as a tourist rather than as a journalist. Did you approach those visits differently than when you had traveled in the past? Elizabeth Becker: Totally….…