The hand with the highest total wins as long as it doesn’t exceed 21; a hand with a higher total than 21 is said to bust or too many. Cards 2 through 10 are worth their face value, and face cards (jack, queen, king) are all worth 10. An ace’s value is 11 unless this would cause the player to bust, in which case it is worth 1. A hand in which an ace’s value is counted as 11 is called a soft hand, because it cannot be busted if the player draws another card.

Each player’s goal is to beat the dealer by having the higher, unbusted hand. Note that if the player busts he loses, even if the dealer also busts. If both the player and the dealer have the same point value, it is called a “push”, and neither player nor dealer wins the hand. Each player has an independent game with the dealer, so it is possible for the dealer to lose to some players but still beat the other players in the same round.
The minimum bet is printed on a sign on the table and varies from casino to casino and table to table. After initial bets are placed, the dealer deals the cards, either from one or two hand-held decks of cards, known as a “pitch” game, or more commonly from a shoe containing four or more decks. The dealer gives two cards to each player including himself. One of the dealer’s two cards is face-up so all the players can see it, and the other is face down. (The face-down card is known as the “hole card”. In European blackjack, the hole card is not actually dealt until the players all play their hands.) The cards are dealt face up from a shoe, or face down if it is a pitch game.

In American blackjack, if the dealer’s face-up card is an ace or a ten-value, the dealer checks his hole card to see if he has blackjack. This check occurs before any of the players play, but after they have been offered insurance (if the face-up card is an ace). If the dealer has blackjack, all players lose their initial bets, except players who also have blackjack, who push. (In some American casinos, the dealer does not actually check the hole card until after the players have all played. At that time, if the dealer turns out to have blackjack, all players who did not have blackjack lose their bets, and players who increased their bets by doubling or splitting lose only the original bet, and have the additional bets returned to them; thus, the end result is precisely as if the dealer had checked the hole card before playing.)

A two-card hand of 21 (an ace plus a ten-value card) is called a “blackjack” or a “natural”, and is an automatic winner (unless the dealer has blackjack as well, in which case the hand is a push). A player with a natural is usually paid 3:2 on his bet. Some casinos pay only 6:5 on blackjacks; although this reduced payout has generally been restricted to single-deck games (Current Blackjack News, Pi Yee Press).
This reduced payout for a natural increases the house advantage over a player by as much as 1000 percent. The move was decried by longtime blackjack players

The player’s options for playing his or her hand are:

* Hit: Take another card.

signal: (handheld) scrape cards against table; (face up) touch finger to table

* Stand: Take no more cards, also “stick” or “stay”.

signal: (handheld) slide cards under bet; (face up) move hand horizontally

* Double down: Increase the wager to a maximum of double the original bet and take exactly one more card. For         example, if the player’s original bet was $25, the player could increase the bet by up to an additional $25, for a new total bet of up to $50. Increasing the wager to less than twice the original bet is called “double down for less”.

signal: place additional chips next to (not on top of) original bet, make “one finger” sign

* Split: Double the wager and have each card be the first card in a new hand. This option is available only when both     cards have the same rank.

signal: place additional chips next to (not on top of) original bet, make “two fingers” sign

* Surrender: Forfeit half the bet and give up the hand.

signal: make ‘chopping’ motion over bet (signal is rare, usually just done verbally)

Hand signals are required in most casinos, so that in case of a dispute, a video record exists of the players decisions.

The player’s turn is over after deciding to stand, doubling down to take a single card, or busting. If the player busts, he or she loses the bet even if the dealer goes on to bust.

After all the players have finished making their decisions, the dealer then reveals his or her hidden hole card and plays the hand. House rules say that the dealer must hit until he or she has at least 17, regardless of what the players have. In some casinos a dealer must also hit a soft 17 (a combination of cards adding up to either 7 or 17, such as an ace and a 6).

If the dealer busts then all remaining players win. Bets are normally paid out at the odds of 1:1. Players who push (tie) with the dealer receive their original bet back. Source: wikipedia.org