What is Blackjack?
A blackjack, or natural, is a total of 21 in your first two cards. A blackjack is therefore an Ace and any ten-valued card, with the additional requirement that these be your first two cards. If you split a pair of Aces for example, and then draw a ten-valued card on one of the Aces, this is not a blackjack, but rather a total of 21. The distinction is important, because a winning blackjack pays the player odds of 3 to 2. A bet of $10 wins $15 if the player makes a blackjack. A player blackjack beats any dealer total other than a dealer's blackjack, including a dealer's regular 21. If both a player and the dealer make blackjack, the hand is a tie or push.
The dealer will usually pay your winning blackjack bet immediately when it is your turn to play. In the face down games, this means that you should show the blackjack to the dealer at that time. Some casinos may postpone paying the blackjack until after the hand is over if the dealer has a 10 card up and has not checked for a dealer blackjack. Other casinos check under both 10 and Ace dealer upcards, and would therefore pay the blackjack immediately. Regardless, when you are dealt a blackjack, turn the cards face up, and smile. It only happens about once every 21 hands, but it accounts for a lot of the fun of the game.