A sportsbook is a place or online site where people can make wagers on sporting events. The word “sportsbook” is sometimes used interchangeably with the words “bookmaker” or “bookie.” A bettor’s choice of sportsbook can have a big impact on the amount of money they win, or lose. A good sportsbook will have a wide selection of betting lines and options, and will also pay out winning bets quickly.

The legality of sportsbooks in the United States varies by state, and is dependent on regulations. Some states have banned sports gambling entirely, while others allow it in real-world brick and mortar establishments, and some even offer legal online sportsbooks. In the latter case, the sportsbooks must verify that a bettor is within their state’s jurisdiction, and may require ID or other forms of identification. In the event of a dispute between a sportsbook and its customer, federal law provides little protection for consumers. Illegal offshore operators, which take advantage of lax or nonexistent laws in countries such as Antigua and Costa Rica, prey on Americans. These unregulated operations do not uphold key principles such as responsible gaming, privacy of consumer funds, and data security. They also avoid paying state and local taxes.

Most sportsbooks offer over/under bets, which are predictions of the total number of points scored in a game. These bets are often available on football and basketball games, but can also be placed on other sports. A sportsbook’s odds may also change for a variety of reasons, including injury or roster news. In some cases, the sportsbook will move a line to attract action, or to reduce liability. Some sportsbooks offer decimal odds, which are more intuitive and easy to work with.