Did the event occur: yes or no?
A proposition bet is a defined outcome bet such as yes or no, up or down, over or under, heads or tails, etc. We sometimes say a proposition bet is a yes or no bet; in the sense that the event either happened or it didn’t.
For example, the 2018 Super Bowl had a proposition bet for whether or not the national anthem would last over or under two minutes in total length. Pink was signing the national anthem and she had never been on record singing the national anthem and, thus, there was plentiful speculation about how long her rendition would last. Everyone sings the national anthem at a different length.
Four of the five national anthems before Super Bowl LII exceeded the two-minute mark. However, on game day Pink finished the anthem at 1 minute and 53 seconds. Everyone who bet “under” won their bets!
Also during Super Bowl LII: there was a proposition bet for what color the Gatorade would be that was poured on the winning coach at the end of the game. Orange, yellow, purple, and clear were all top contenders. Yellow was poured on Coach Pederson—everyone who bet yellow was a happy camper that day.
We also see bettors place bets on whether the coin toss for certain sporting events will be heads or tails. You can place a prop bet on just about anything!
It’s a defined outcome bet. There can be more than two choices. It’s yes or no in the sense that it either happened or it didn’t. There can be multiple did not happen options; such as the Gatorade was not orange, purple, or clear.
A proposition bet pulls bettors out of the overall event (focused on totals or spreads), and allows a bettor to bet on one particular item.