Tourism is travel for recreational, leisure, or business purposes. The World Tourism Organization defines tourists as people "traveling to and staying in places outside their usual environment for not more than one consecutive year for leisure, business and other purposes".

Tourism has become a popular global leisure activity. After slowly recovering from the contraction resulting from the late-2000s recession, where tourism suffered a strong slowdown from the second half of 2008 through the end of 2009, and the the outbreak of the H1N1 influenza virus, international tourist arrivals surpassed the milestone 1 billion tourist globally for first time in history in 2012. International tourism receipts (the travel item of the balance of payments) grew to US$1.03 trillion (€740 billion) in 2011, corresponding to an increase in real terms of 3.8% from 2010. In 2012, China became the largest spender in international tourism globally with US$102 billion, surpassing Germany and United States. China and emerging markets significantly increase their spending over the past decade, with Russia and Brazil as noteworthy examples.