A Quinella wager involves picking two horses, and you are a winner if they come in first and second in the race in any order.
If you choose the #1 and #2 horse, you are a winner on a Quinella bet if they finish #1-#2 or #2-#1. The payoff is the same regardless of which order they come in.
In a Quinella box, you must choose three or more horses. If two of these three or more horses finish first and second, you are a winner. So if you go with the #1,#2,#3 horses, you will win as long as two of the three finish in the first and second spot.
Not all tracks offer Quinellas.
Keep in mind that the payoff will be the same whether it comes out #1-#2 or #2-#1. That differs from an Exacta box. If you like two horses and play an Exacta box and your first choice is a longshot and your other choice is a favorite, in most cases you will be rewarded more if your longshot gets the win.
For example, say a 10/1 longshot wins the race and the 5/2 favorite runs second. The Exacta might return $60. If the 5/2 favorite wins with the 10/1 longshot running second, the Exacta would probably pay around $30.
The Quinella would pay the same regardless of which of the two won the race.
Bettors with smaller bankrolls like the Quinella because you can cover two horses with just a $2 wager. A $2 Quinella box using three horses is just a $6 wager. But more and more tracks now offer $1 Exactas, and in the long run a horseplayer is probably better off playing Exacta boxes as opposed to playing the Quinella.
But as you learn to watch the probable payoffs located on the tote board and the television monitors, you may want to do some comparative pricing and watch the payoffs. You can on occasion find spots where the Quinella may end up offering better value.