A sportsbook is a specialized service that accepts bets on a variety of sporting events. A full-service racebook and casino frequently accompany a sportsbook, making it a one-stop shop for betting on everything from horse races to America’s most popular pro and college sports. Online betting sites make it easy to place bets from anywhere in the world with a few clicks of the mouse, and many offer mobile apps for convenient, on-the-go access.

As the popularity of gambling grows in the United States, sportsbooks work to ensure that their products are well regulated. Responsible gambling tools include betting limits, warnings and time counters that help keep recreation from turning into addiction. Increasingly, the industry is also focusing on early indicators that a player is starting to have a problem.

For example, since PASPA was overturned, legal sportsbooks have collected $14 billion in gross revenue from bettors, and on average they’ve paid out $17 for every dollar they’ve taken in wagers. But winning seems to be more common than losing: Players crow about their $1,000 win on the Packers-Bears spread last weekend, but rarely mention that they lost $500 each of the three previous weekends.

The odds for any given bet are calculated by a sportsbook’s head oddsmaker, who draws on information from computer algorithms, power rankings and outside consultants to set prices. A sportsbook typically uses a third-party vendor to supply its odds or has an in-house development team. American odds are based on $100 bets and vary based on the expected winning percentage for each side of a bet.