Definition
A sportsbook is a licensed company or platform that accepts sports bets, posts odds, pays winning tickets, and keeps losing stakes. It can operate online, in a retail location, or both. The sportsbook sets betting markets such as moneylines, point spreads, totals, props, futures, and live bets.
A sportsbook builds margin into its odds. For example, two evenly matched teams might both be listed at -110 instead of +100. At -110 odds, the payout formula is:
Stake / 110 x 100 = profit
Worked Example
A bettor places $110 on Team A -110 against the spread.
If Team A covers, the bettor wins $100 in profit and receives $210 total back: the original $110 stake plus $100 profit.
If Team A does not cover, the sportsbook keeps the $110 stake.
If both sides of the same game are priced at -110, the sportsbook is charging a margin because it collects $110 from a losing bettor while paying $100 profit to a winning bettor.
Why It Matters
Understanding what a sportsbook does helps a bettor separate the posted odds from the true price of a bet. This concept matters when comparing lines across books, checking payout math, and identifying which price gives the best value.