A bookmaker (also called a sportsbook or bookie) is an organization or individual that accepts bets on sporting and other events at agreed-upon odds. Licensed bookmakers are regulated by gambling authorities and must meet specific standards for fairness and player protection.
Choosing a properly licensed bookmaker ensures regulatory oversight, fair odds calculation, secure transactions, and access to dispute resolution mechanisms if problems arise.
A licensed bookmaker offers odds on a tennis match: Player A at 1.75 and Player B at 2.10. The bookmaker builds in a margin (overround) to ensure profitability regardless of the outcome.