Pari-mutuel betting is a form of betting in which all bets are pooled together and the winners are determined by dividing the pool among those who have bet on the winning outcome. It is different from fixed-odds betting, where the payout is predetermined at the time of the bet. Pari-mutuel betting is popular in horse racing, greyhound racing, and other sports. It is also used in some lotteries and other forms of gambling.