A sportsbook is a gambling establishment that accepts wagers on various sporting events. It can be located on the premises of a casino or other licensed establishment, such as on a cruise ship, or over the Internet. It takes a percentage of all bets made by customers, or “action”, through vigorish (vig). While some physical sportsbooks are affiliated with casinos in Las Vegas and only take action from hotel guests and recreational gamblers, many operate as standalone businesses, taking bets over the Internet, via telephone, or on self-serve kiosks. Most legal online sportsbooks use a customized software platform to take the action from their clients.

In order to maximize profits, a sportsbook must have an excellent record keeping system in place. It also needs to offer a variety of betting markets, including ante-post and match-up odds. It should also cover a range of leagues and events, from major football to Challenger events in tennis.

The best online sportsbooks provide a steady stream of promotional offers to attract new players and reward loyal customers. These include first bet offers, odds boosts and insurance offers on parlays and props. These offers help sportsbooks reduce their house edge and increase their chances of turning a profit.