Parlay is a term that implies several meanings at once. It usually refers to an combo bet (a bet that combines several bets at once). The second meaning of the term is a betting strategy.
The term was formed from the word parlay, which means “to argue, to keep a bet”. Despite its original meaning, it usually refers to combo bets. To conclude a Parlay, the player has to choose a chain of bets, and if at least one of them loses, it is not possible to take the winnings. Although there are varieties of parlays, where the rules are more flexible.
If we take another definition of the term, that is, betting strategy, it is about doubling the bet after each successful outcome.
Suppose a bettor bet $1 on an event with odds of 2.0. With a successful outcome, the winnings will be a dollar, but with Parlay strategy there will be a doubling, and the account will be $2. Next, the punter bets $2, and if he wins, his account will be $4.
This is a very successful strategy, if the bettor has the goal of winning a large sum in a short time and with a minimum bank. However, a loss with Parlay is also significant, so it is necessary to act reasonably according to the strategy.
