What Is a Sportsbook?

A sportsbook is a licensed business, retail or online, that accepts wagers on the outcome of sporting events and pays out winning bettors based on odds it sets in advance. In the United States, a legal sportsbook operates under a state gaming license, follows that state's rules on who can bet and how much, and builds a small built in fee, called the vig, into its odds instead of charging a visible commission. If a business takes sports bets without a license from a US state or tribal regulator, it is an offshore or unlicensed operation, not a legal sportsbook, no matter what it calls itself.

Key stats: sportsbooks at a glance

• 38+ states plus Washington DC have legalized some form of sports betting as of 2026, according to Legal Sports Report's state by state tracker.
• $78.7 billion in commercial gaming revenue was generated across the US in 2025, a record, per the American Gaming Association's State of the States 2025 report.
• -110 is the standard price most legal sportsbooks set on each side of a spread or total, which bakes in roughly 4.5 percent vig before you even place the bet.

How does a sportsbook work?

A sportsbook works by setting a price, called odds, on a possible outcome, then collecting bets on both sides of that outcome so it profits from the margin built into the price rather than from picking winners. On a typical NFL spread, a sportsbook will offer both sides at -110, meaning a bettor risks $110 to win $100. If it takes roughly equal action on both sides, the book keeps the difference regardless of which side wins. That built in margin is the vig, and it is the single biggest cost of betting that most casual bettors never notice. VigVerdict has a full breakdown in what vig means in sports betting and how to calculate it.

What does a sportsbook actually do?

A sportsbook sets betting lines, accepts and settles wagers, manages risk across its whole book of bets, and pays out winners. Behind the scenes, most US sportsbooks do not set every line from scratch. They license a base set of odds from a pricing provider, then adjust those lines based on their own betting volume, injury news, and line movement at competing books. That is why the same game can carry slightly different odds at DraftKings, FanDuel, or BetMGM at the same moment.

Sportsbook vs casino vs bookie: what is the difference?

A sportsbook only takes bets on sports outcomes. A casino, online or retail, offers games like slots and table games where the house has a fixed statistical edge instead of a two sided market. A bookie is an unlicensed individual or operation taking sports bets outside of any state regulatory system, which is illegal in every US state regardless of how it is marketed. The table below summarizes the difference.

Type	What it offers	Regulated in the US
Licensed sportsbook	Bets on sporting event outcomes at set odds	Yes, state by state
Online casino	Slots, table games, live dealer games	Yes, in select states only
Bookie or offshore site	Sports bets outside any state license	No, illegal to operate and risky to use

How do sportsbooks make money?

Sportsbooks make money primarily through the vig, the small percentage built into the odds on every bet, not by rooting for one team to lose. A well run sportsbook tries to balance its liability on both sides of a game so it collects the vig no matter the outcome. Secondary revenue comes from same game parlays and prop bets, which usually carry a higher built in margin than a straight spread or total, and from promotional structures that encourage more betting volume. None of this requires the book to be biased against you on a single bet, but it does mean the price you are offered is never perfectly fair.

What is the difference between a sportsbook and a betting exchange?

A traditional sportsbook sets its own odds and bets against its customers, while a betting exchange lets bettors wager against each other and simply charges a commission on winning bets. Betting exchanges are common in the UK but have limited availability in the regulated US market, where the standard model is the traditional sportsbook.

Is an online sportsbook the same as a mobile betting app?

Yes. An online sportsbook and a mobile sportsbook app are the same product accessed through different screens. Every major legal US operator, including DraftKings, FanDuel, BetMGM, Caesars, and Fanatics, runs its online sportsbook primarily through a mobile app, with a desktop website offering the same betting markets.

How do you use a sportsbook for the first time?

Using a legal sportsbook for the first time follows the same basic pattern at nearly every regulated operator.

• Confirm sports betting is legal in your state and that you are at least 21 (18 in a small number of states).
• Create an account and verify your identity, which is required by state regulators to prevent underage and out of state betting.
• Deposit funds using a bank transfer, debit card, PayPal, or another supported method.
• Browse the odds board, pick a bet, and confirm your stake before submitting.
• Withdraw winnings back to your original payment method, which typically takes anywhere from same day to a few business days depending on the book.

Are sportsbooks legal in every state?

No. Sports betting is legal in most, but not all, US states. As of 2026, more than 38 states plus Washington DC have some form of legal sports betting, either online, retail only, or both, while a handful of states, including California, Texas, and Georgia, have not legalized it. Rules also vary by state on minimum age, which sports can be bet on, and whether online betting is allowed at all. Check your own state regulator before signing up anywhere, and never use a site that is not licensed where you live.

Illustrative example, not an attributed quote: a state gaming regulator explaining licensing to a new bettor might put it simply as, "If the sportsbook cannot show you a license number from our state, it cannot legally take your bet, no matter how professional the app looks."

Frequently asked questions

What is a sportsbook in simple terms?

A sportsbook is a business that lets you bet money on the outcome of a sports event and pays you if your prediction is correct, based on odds it sets ahead of time.

Is a sportsbook the same as gambling?

Sports betting through a sportsbook is a form of gambling. It carries real financial risk, and outcomes are never guaranteed no matter how confident a bettor feels about a pick.

How do I know if a sportsbook is legal?

A legal US sportsbook will display its state license information, typically in the footer of its website or app, and will require identity verification before you can deposit or withdraw. If a site skips identity checks or will not name its licensing state, treat it as unlicensed.

Can I use more than one sportsbook at a time?

Yes. Most bettors in legal states use two or three regulated sportsbooks so they can compare odds and take the best available price on a given bet, a practice known as line shopping.

Do sportsbooks always win?

Sportsbooks do not always win on every individual bet, but the vig built into their pricing gives them a structural edge over time across their full customer base, similar to how a casino's house edge works on games of chance.

Updated July 2026. VigVerdict only reviews and discusses regulated, state licensed sportsbooks. To see how specific books compare on pricing and features, read our FanDuel vs DraftKings comparison or browse our full sportsbook reviews.

Play responsibly. You must be 21 or older (18 or older in a small number of states) and located in a state where sports betting is legal to use a sportsbook. Bet only what you can afford to lose. If you or someone you know has a gambling problem, call or text the National Problem Gambling Helpline at 1-800-GAMBLER.