What is gambling? Merriam-Webster's dictionary gives half a dozen definitions, including playing a game of chance for money and making a bet on an uncertain outcome. One definition says that gambling is staking something on a contingency. Another says that gambling is taking an action with an element of risk. Combining various terms together provides the following overall definition: Gambling is an activity in which something of value is risked on the chance that something of greater value might be obtained, based on the uncertain outcome of a particular event.

Organized gambling has become an industry because so many people are willing and even eager to risk their money in exchange for a chance at something bigger and better. The elements of risk and uncertainty actually add to gambling's appeal—and to its danger. Throughout history, various cultures have considered gambling harmless, sinful, respectable, corrupt, legal, illegal, and tolerable. Some people love it, some people hate it, and some people just ignore it. Societal attitudes are dependent on cultural issues such as customs, traditions, religion, morals, and the context in which gambling occurs.

In 1999 the Gallup Organization quizzed 1,523 adults on whether they considered the following activities to be gambling: buying lottery tickets, playing poker with friends for money, participating in office pools, playing church-sponsored bingo, and investing in the stock market. The largest majority (78%) considered buying lottery tickets to be gambling. Only 59% considered playing church-sponsored bingo to be gambling, and just over half (52%) believed that investing in the stock market is gambling.

Lawmakers have struggled to define gambling and determine which activities should be legal and which should not. For example, betting activities with an element of skill involved (such as picking a horse in a race or playing a card game) might be more acceptable than those based entirely on chance (such as spinning a roulette wheel or playing slot machines). Acceptability also depends on who profits from the gambling. Bingo games held for charity and lotteries that fund state programs are more commonly legal than casinos run for corporate profit.

In the article "In Defense of Gambling" (Forbes, June 23, 2003), Dan Seligman estimated that Americans legally gamble approximately $900 billion a year. According to findings reported in the National Gambling Impact Study Commission Report (1999), illegal gambling levels could be as high as $380 billion per year. This means Americans gamble more than $1 trillion per year. But why do people gamble at all? Common sense suggests that risking something of value on an event with an uncertain outcome is irrational. Scientists who study gambling give a variety of reasons why people gamble, including the lure of money, the excitement and fun of the activity, and influence from peers. At its deepest level, gambling may represent a human desire to control the randomness that seems to permeate life. Whatever the drive may be, it must be strong. An entire gambling culture has developed in America in which entrepreneurs (legal and otherwise) offer people opportunities to gamble, and business is booming.