A sportsbook is a gambling establishment that accepts bets on various sports events and teams. These businesses are regulated by government agencies and must adhere to responsible gambling rules in order to protect their customers. They also must implement anti-addiction measures, such as betting limits, warnings, time counters, daily limits, and so on. In the US, DraftKings was one of the first operators to launch an online sportsbook after the Supreme Court overturned the federal wagering ban PASPA in 2018.

The legality of a sportsbook is determined by state law and gambling regulators. Generally, sportsbooks must have at least $100,000 in working capital to start operations and must register with the gaming commission or tax authority. However, there are some states that allow sportsbooks to operate without a license. These are known as “bookie shops.”

In addition to adjusting the odds of against-the-spread bets, sportsbooks also move totals in over/under and prop bets. For example, if a sportsbook receives a lot of action on the over side of a Patrick Mahomes touchdown total that opened at 249.5 yards, they can lower the odds (say from -110 to -125) and raise the total (to 252.5) to induce more action on the under.

Another way for a sportsbook to grow is by setting up a referral program. This typically involves rewarding current customers with a financial reward for each new customer they refer to the sportsbook. This is a popular growth strategy that can help to drive revenue and build brand awareness. In addition, a referral program can be used to monitor player behavior and ensure that fraudulent activity is not occurring on the site.