Hole Card in Blackjack
The hole card is the dealer's face-down card. While the upcard is visible to all players, the hole card remains hidden until after all players finish their hands.

The hidden card (not shown above) is the hole card.
When the Hole Card Is Revealed
The dealer flips their hole card only after all players have completed their hands (hit, stand, bust, etc.).
Exception: When the dealer shows an Ace or 10-value card, they check for blackjack before players act. If they have blackjack, the hand ends immediately.
Peek vs. No-Peek Rules
American (peek) rules: Dealer checks the hole card when showing Ace or 10. If they have blackjack, no more bets are lost on splits/doubles.
European (no-peek) rules: Dealer doesn't check. If dealer has blackjack, you lose all bets including splits and doubles.
Strategy Implication
You can't see the hole card, so basic strategy is based on probabilities. The upcard gives you enough information to make the mathematically best decision.
