Dark Bet
A dark bet is a bet announced before the next card is dealt.
The simple explanation
In a dark bet, a player announces a bet for the next round before the dealer deals the next card. The bet is binding regardless of what card comes. It is also called betting in the dark.
A closer look
The player who bets in the dark must be first to act in the next round. For example, in hold'em, a preflop raiser who says 'I bet $100 in the dark' will make a $100 bet on the flop whatever the flop is. The move gives up information and signals confidence, but it also prevents opponents from betting first.
A practical example
A player raises, another calls, and the raiser says 'I bet $100 in the dark' before the flop is dealt.
Full explanation
A dark bet is a bet announced before the next card is dealt.
A dark bet is announced before the next card or cards are dealt. The bettor does not wait to see the flop, turn or river.
The announced bet is binding, whatever card appears. If the bettor wants to change the bet after seeing the card, the rules do not allow it.
The bettor must be first to act in the coming round. That is a condition of the move, since it can only work if the bettor acts before everyone else.
The move is rare in modern games.