A sportsbook is an establishment that accepts wagers on various sports events at pre-set odds. It is regulated to ensure fair play, prevent underage gambling, money laundering and other issues. It also ensures responsible gambling by offering tools like time counters, betting limits and warnings to its users. In the United States, sports betting was legalized in 2018 and many sportsbooks have made their way into the online marketplace.

The most common type of sportsbook is an online one, which allows bettors to place bets at their own convenience without having to physically visit the sportsbook. There are also some offline sportsbooks in the US, but most people use online ones because they are more convenient and offer a much wider range of betting markets.

Odds at sportsbooks are set by the head oddsmaker. They typically rely on power rankings, computer algorithms and outside consultants to establish their prices. They are based on the probability that an event will occur but can differ depending on how much action is expected on each side of a bet.

Because of this, it is important to shop around at different sportsbooks. This is part of money management 101 and is critical to long-term profitability. The best sportsbooks will provide closing line value, which is a metric that measures how much more a player could win if they were to place a bet on the same team at another book before the game starts.