In big bet poker, it is possible to reach a situation in which you are uncomfortable with the amount of money you have invested in a pot. To reduce variance, players will sometimes take insurance against an unfortunate outcome, essentially selling the actual outcome of the hand for its mathematical equity (at a slight discount). For example, if you hold a flush against a player who has three of a kind, your equity in the pot is a percentage of the pot equal to the probability that the other player will not fill up. If the pot is large, and you don't want to risk coming away with nothing, you might take insurance from somebody who has more money and would be glad to have the overlay.