A sportsbook is an establishment that accepts wagers on sporting events and pays winning bettors an amount that varies according to the likelihood of the outcome. Historically, sportsbooks have operated in brick-and-mortar locations or by phone; today, many operate solely online. They accept bets on major sports, as well as eSports and pivotal world events.

Setting odds is one of the most important duties of a sportsbook. These odds are designed to help sportsbooks balance the amount of money placed on each side of a bet, so that they can collect the same amount of money from bettors regardless of whether the bets win or lose. In order to achieve this goal, sportsbooks set their odds based on the results of previous games and historical betting patterns. They also use a margin known as the vig, which covers overhead costs such as rent, payroll, and software.

While all sportsbooks are different, they all share some essential similarities. For instance, they all offer odds on the probability of an event occurring. They also provide a variety of betting options, including point spreads and moneyline odds. Point-spread odds reflect the true expected probability of an event, while moneyline odds show how much a bettor can expect to win on every $100 bet they make.

Another common feature is live betting, which allows bettors to place bets in real time while the game is still in progress. Sportsbooks also offer IF bets, which are a series of bets that will pay out if the first bet wins. IF bets are also called “multi-bets” and can be very profitable for sportsbook operators.