Official betting is a form of gambling in which you place a bet on the outcome of a sports event or competition. Bets can be placed on a variety of outcomes, including winning teams, individual players and game totals. Betting odds are displayed in decimal, fractional and American forms and indicate the probability that a particular outcome will occur. The more money placed on a certain result, the lower the odds will be. Odds can also be grouped together to form a combination wager, such as an “exacta” (picking the first two finishers in exact order) or a “quinella” (picking the first three finishers in any order). Hitting a combination wager can lead to enormous payouts.

Gambling on sports is illegal in most countries and some professional leagues. In Major League Baseball, for example, any player, umpire or club or league employee who bets on a game in which he has a duty to perform is automatically banned from the game and ineligible for the Hall of Fame. Joseph Sullivan, an early-century bookmaker and gambler, is credited with the 1919 Black Sox Scandal, in which he paid eight members of the Chicago White Sox—Oscar Felsch, Arnold Gandil, Shoeless Joe Jackson, Fred McMullin, George Weaver, Charles Risberg, and Claude Williams—around $10,000 each to fix the World Series.

Sports betting is legal in Connecticut, Delaware and Nevada. It launched in Delaware in 2018 and was introduced in Colorado in 2021. The state’s 2022 legislation includes a provision for online sports betting. However, betting on in-state collegiate games and player prop bets are prohibited.