Bottom dealing is a cheating technique in which the dealer deals cards from the bottom of the deck instead of the top. This allows the dealer or a player working in collusion with the dealer to know what card is coming next and can give them an unfair advantage in the game. Bottom dealing is considered to be one of the most serious forms of cheating in poker and is illegal in all forms of the game. Casinos and poker rooms take strong measures to prevent cheating and catch any players who attempt to use such tactics.