A wildcard in gambling refers to a special card or symbol that can represent other cards or symbols to create winning combinations. This concept is commonly found in games like poker and slot machines, where wildcards can enhance the player's chances of winning by substituting for missing elements in a hand or sequence. In addition to card games, wildcards can also appear in lottery games and sports betting. They add an element of surprise and excitement, as players may not know when a wildcard will come into play, potentially changing the outcome of the game or bet.