In poker, a bean or an ante bean is a term that refers to the ante or the chip that is used to place the ante. An ante is basically a forced bet that kicks off each round – each player puts an equal amount of money or chips into the pot before the first cards are dealt. Aside from a tournament setting, the ante is very small – usually a single unit (a one-value chip, or the smallest value in play) or up to a half of the minimum bet.
If the ante is set at $1 and there are four players sitting at the poker table, each of them has to place a $1 chip in order to continue playing the game. Therefore, once all the “beans” are in, the pot is worth $4 regardless of the blinds and/or bets that would be placed later on.
Players are required to “place the beans” to ensure that every participant of the game that decides to fold will lose some money. Therefore, everyone has an incentive to play the hand instead of throwing away all but the strongest starting hands.
In tournament games, the ante usually grows quite fast, which forces participants to play a considerably riskier and more aggressive game, arguably making poker tournaments more entertaining to watch.