For too long, argues the author Elizabeth Becker, the tourism industry has been treated as anything but. Tourists, she writes in her highly readable new tome, Overbooked: The Exploding Business of Travel and Tourism, rarely think of travel \"as one of the world\'s biggest businesses, an often cut-throat, high-risk and high-profit industry\". Instead, they\'re thinking about suntans, new locales, \"and the liberating freedom of taking a break from their own lives\", Becker maintains. It may surprise many of the sunburnt beachgoers out there that tourism is the biggest - that\'s right, the biggest - industry in the world. In 2007, the first global accounting system revealed that tourism contributed US$7 trillion to the world economy and was (and is) the largest employer, with 250 million associated jobs. Clearly, \"global\" becomes \"local\", because tourism can have a huge impact on the economies of the world\'s poorer nations, such as Zambia, Cambodia and Sri Lanka - all of which figure into Overbooked - as well as richer nations such as the United States, China and France (now the planet\'s number one destination). Travel, moreover, has global political and philanthropic implications. \"Tourism is the greatest modern voluntary transfer of wealth from rich countries to poor countries,\" declares David Hawkins of George Washington University in Washington, DC. Hawkins, who is the institution\'s Eisenhower professor of tourism, once represented the US before the UN World Tourism Organization - yes, there actually is such a body - until the US pulled out for political reasons, but more on that later. The point is that it has become difficult for the UN or any other entity to measure, much less control, worldwide tourism, the \"octopus-like\" tentacles of which, Becker points out, now embrace issues as diverse as coastal development, child prostitution, the treatment of religious monuments, and the survival of threatened bird species and native cultures. There is even \"dark\" tourism (meaning the fascination many people have with places like Cambodia\'s notorious Tuol Seng prison, the torture/execution centre run by the Khmer Rouge). Lighter categories, such as shopping tourism, figure in as well, says Becker, who jumps off here for a chapter about Dubai and its particularly rich retail opportunities. \"Today, Dubai is considered a model for tourism in the 21st century,\" Becker writes, calling the city\'s malls legendary for selling more brand names than anywhere but London. Dubai also welcomes three times as many foreigners as New York City, she notes. But UAE readers may not be as pleased with the rest of the author\'s message. \"A journey through Dubai - and Abu Dhabi - is a practical course in tourism and its future. It is a pretty frightening one, too,\" she writes, opining that Dubai and the Emirates in general \"are models for the overconsumption that is threatening the planet\". She underscores that stance by describing how Dubai has strived to become one of the major hubs in the airline world - Dubai International is set to be the world\'s busiest airport by 2015 - and how more energy per person is expended there than almost anywhere in the world. Still, other nations are also taking notice and looking at ways to mine their own unique riches and thus boost tourism along with their economies. Zambia is a good example, given its elephants, baboons and hippos, which bring in safari-minded tourists. Copper is still king in Zambia, but tourism to this African nation contributes $1 billion a year and that figure is growing. Becker focuses on South Luangwa National Park, where from 1975 to 1989 the elephant population was decimated, until conservation became a priority, not only to save these magnificent creatures but to save tourism.