A parlay, accumulator (or acca), combo bet or multi is a single bet that links together two or more individual wagers and is dependent on all of those wagers winning together. The benefit of the parlay is that there are much higher pay-offs than placing each individual bet separately since the likelihood of hitting all of them at once is much less. If any of the bets in the parlay lose, the entire parlay loses. If any of the plays in the parlay ties, or "pushes", the parlay reverts to a lower number of teams with the odds reducing accordingly. In order to win a parlay, every wager within it must win.

Although a variety of bets can be used to build a parlay bet, correlated parlays are usually not allowed at betting sites. Correlated parlays are two or more bets from the same game that relies on a closely related outcome. Sportsbooks restrict this action because closely related bets can lead to bigger payouts in the chance of a win, which means a more substantial loss for the sportsbook.