A sportsbook is a gambling establishment that accepts bets on various sporting events and pays winning bettors an amount that varies depending on the odds. The term is most commonly used to refer to a legalized sportsbook that takes wagers on major US leagues and some international competitions. The best sportsbooks offer a variety of betting markets, ranging from straight bets to parlays and exotic bets. They also use reputable software that works on desktop and mobile browsers on iPhones and Android devices.

In addition to accepting bets on all major sports, some online sportsbooks offer a variety of niche markets, including esports and entertainment (e.g. the Academy Awards). Many of these sites are based in Nevada and operate as legally sanctioned bookmakers. Others are regulated by state authorities and use software that is tested for security.

There are a number of different types of bets available at sportsbooks, but most bettors place straight bets, which are wagers on the outcome of a single event. For example, if the Toronto Raptors are playing Boston Celtics in an NBA game, and you think the Raptors will win, then you’d make a straight bet on Toronto to win.

Sportsbooks set their odds based on probability, which is calculated as the probability of an event occurring divided by the total number of bets placed on it. They also include their commission in those odds to ensure they’ll make money over time. This allows bettors to compare odds from different sportsbooks and choose the best one for them.