In blackjack, the dealer's hole card is the face-down card dealt to the dealer, remaining hidden from players until the dealer's turn is complete. The dealer receives two cards: one face-up (the upcard) and one face-down (the hole card). The value of the hole card is crucial as it determines the dealer's total hand value. If the upcard is a 10 or an ace, the dealer checks for a blackjack. If the dealer has a blackjack, the round ends, and players lose their bets unless they also have a blackjack, resulting in a push. If not, play continues, and the dealer reveals the hole card, hitting or standing based on house rules. The outcome is then determined by comparing the final hand values of the dealer and the players.