The Black Jack (also known as Twenty-one in Italian) is a gambling card that takes place between the bank, represented by the casino, and players. They win the players who make a higher score bench no more than 21.
The game originated in France in the seventeenth century, with the name of vingt-et-un (or "twenty-one"). Once arrived in the United States the game of twenty-one was called Black Jack (jack black) with the introduction of a variant: if the player did a 21 with an ace and jack of spades, was paid a bonus of ten times the mail . Although currently the bonus was abolished, however, the name has stuck.
Black Jack is normally used with a shoe size of 2 decks of cards in France, for a total of 104 cards. In the game, the ace can be worth 11 or 1, face cards are worth 10, while the other cards are worth their face value. The seeds have no influence or value. The sum of the points, in order to calculate the score, is by simple arithmetic.
Playing the game
Once the players have made their bet, the banker from left to right give each player one card at each location played, giving the last bench. Then made a second round of cards face up, without attributing one to oneself. The distribution took place, the dealer law regarding the score of each player inviting them to express their game: they will be able to hit or stay at their discretion. If a player exceeds 21 is a loser and the dealer will collect your bet. Once players have defined their scores the dealer develops his game following the "rule of the bench": he must roll paper with a score of less than or equal to 16. Once you pass 16 you must stop. If the counter exceeds the 21 "bust" and must pay all bets remain on the table. Once all the scores, the dealer compares his own with one of the other players, pays combinations superior to his own, retires and leaves the lower ones in a draw. The payment of winning bets is on par.
The Black Jack pure
The Black Jack pure is obtained when the player makes 21 with the first two cards assigned by the dealer, and you can only do with an Ace of Spades (11) and a Jack of spades; This score beats the dealer even though totals 21.
The Black Jack
The player who makes 21 with the first two cards assigned by the dealer, that receives an Ace (11) and a ten or a shape, form, blackjack and is entitled to payment of 3 to 2 (one and a half times the mail, that is, , the stake x 1.5); if the dealer also makes him the Blackjack hand is considered equal.
The doubling of the bet (double down)
Players have played a particular option: if the first two cards are made from 9 to 15 points, they can double your bet when you call but pledging to ask for a single card, and after receiving this card, the player is obliged to stop.
The division (split)
If the first distribution, the player receives two cards of the same value can make the split and that is:
separate the two cards and add an equal bet on the second;
continue the game as if the player had the first two cards;
add a card on each separate card.
In the case of two Aces double play is allowed but with the right to a single call.
Strategy for the split
The "split" in the size of the British game does not place limits on the number of divisions equal card even though it is forbidden the player to "split" the four, five and figures, that the institution of rules of the game in Britain has assessed statistically disadvantageous as betting against the player. A good blackjack player can if necessary be "split" four and five but should never dare to split the two figures.
When the banker serves as an Ace up card, there is the possibility that face Black Jack with the second card, so players may resort-insurance. The stakes of the insurance bet is half the base (the one on the box, for example: If the player has bet the insurance is worth 50 100). If the dealer achieves Black Jack the player will lose all of your initial bet, but will be compensated with twice the value of the insurance (2:1): in practice, it is as if the hand would end with an "equal". If the dealer does not make a Black Jack insurance will be canceled regardless of the outcome of the hand.
The different versions
In Europoa the cards are dealt, two for each player, one for the bench. In the U.S. also, the dealer, in addition to its face-up card, immediately took the other, which remains covered.
In various casinos can be "split" (separate) cards equal to three times, except the axes which can be separated only once. After the split you can often (but not everywhere) to double your bet. In general, you can not double your hands soft (an ace with a card that is not shown). However, there are casinos that allow you to double down on any initial combination.
Among the variants of Blackjack are: Classic, European, Spanish 21, Vegas Strip, Atlantic City, Blackjack Switch, Multi-hand.
The strategy of the game varies depending on the local rules and number of decks used. Beyond the choice whether to participate in the game, and the bet placed in one hand and the ability to double the stakes, the only choice left to the player to decide whether to ask for another card (and, if the first two cards are the same, to make a split, that is to split your hand into two).
To carry out the calculations of probabilities in various situations have been used as some of the first computers available to the university. In particular at MIT have been made several studies in this field. Based on these calculations, it is now possible, based only on what cards you have in your hand to know what the probability of getting any kind of paper. Based on these probabilities, was calculated by a rule (Basic Strategy) that determines which is the best decision to be made in different circumstances. Everything is explained in the section win with the Blackjack
These calculations and this rule is based solely on the cards in play at that time. However, it is possible to develop a further strategy due to the fact that the number of cards at the table (ie, the number of decks used) is fixed and the fact that the cards are shuffled only at the beginning of the game and continue to play in one hand and the other without reshuffle the cards, but continuing to use the remaining cards in the deck. The cards are shuffled only when you reach the cardboard divider that is usually placed around the middle of the shoe. This paper partition determines the percentage of deck penetration, ie the number of cards that will be distributed (with respect to the total present in bunches) that takes place before the shuffle. More than this percentage is high, and the greater the benefits to the player. 
It is therefore possible, although very difficult to remember which cards have already come to know and then which remain in the deck. The high number of cards used makes it difficult to remember each card individually; However, it is possible (though still hard) to remember if outputs from the deck are more low cards than high value cards and consequently calculate the probability that a card drawn from the deck is of high or low value. This technique is indicated with the name of card counting.
A situation with a deck of cards with more high cards than low is favorable to the player and unfavorable to the bank (because it increases the likelihood of a bank of over 21, since the bank is acting in a fixed way, which is to continue to take a 'additional paper as long as it does not exceed or until all players get to 17, and for other reasons). This technique allows therefore difficult to know what is the most propitious time to make higher stakes.
Black Jack, there are also some versions to be played between all players, in which the part of the dealer is alternated between the various players. Inside the casinos instead the role of the dealer is always held by the house staff.