Blackjack

Blackjack (also known as Twenty-one, Vingt-et-un (French for Twenty-one), or Pontoon) is the most widely played Casino banking game in the world. Much of Blackjack's popularity is due to the mix of chance with elements of skill, and the publicity that surrounds Card Counting (calculating the probability of advantages based on the ratio of high cards to low cards). The casino version of the game should not be confused with the British card game Black Jack (a variant of Crazy Eights).

History of Blackjack
Blackjack's precursor was "twenty-one", a game of unknown origin. The first written reference is to be found in a book of Miguel de Cervantes, the author of Don Quixote, and a gambler himself. The main characters of his tale "Rinconete y Cortadillo", from "Novelas Ejemplares", are a couple of cheaters working in Seville. They are proficient at cheating at "veintiuna" (Spanish for twenty-one), and stated that the object of the game is to reach 21 points without busting, and that the Ace values 1 or 11. The game is played with the spanish deck, that is without tens, which makes the game similar to the current spanish 21. This short story was written between 1601 and 1602, so the game was played in Castilia since the beginning of the 17th Century or even earlier. Later references of this game are to be found in France and Spain.

When 21 was first introduced in the United States it was not very popular, so gambling houses tried offering various bonus payouts to get the players to the tables. One such bonus was a 10-to-1 payout if the player's hand consisted of the ace of spades and a black Jack (either the Jack of clubs or the Jack of spades). This hand was called a "blackjack" and the name stuck to the game even though the bonus payout was soon abolished. As the game is currently played, a "blackjack" may not necessarily contain a jack or any black cards at all.

How to play blackjack
In casino blackjack, the dealer faces one to seven players from behind a kidney-shaped table. Each player plays his hand independently against the dealer. At the beginning of each round, the player places a bet in the "betting box" and receives an initial hand of two cards. The object of the game is to get a higher card total than the dealer, but without going over 21 which is called "busting" or "too many." (The spot cards count 2 to 9; the 10, jack, queen, and king count as ten; an ace can be either 1 or 11.) The player goes first and plays his hand by taking additional cards if he desires. If he busts, he loses. Then the dealer plays her hand. If the dealer busts, she loses to all remaining players. If neither busts, the higher hand total wins. In case of a tie, no one wins - the hand is a "push." It is possible for the dealer to lose to some players but still beat other players in the same round. Cards are dealt in two ways, either from one or two hand-held decks, or from a box containing four to eight decks called a "shoe." When dealt by hand, the player's two initial cards are face-down, while the dealer has one face-up card called the "upcard" and one face-down card called the "hole card." (In European blackjack, the hole card is not actually dealt until the players all play their hands.) When dealt from a shoe, all player cards are normally dealt face-up, with minor exceptions. It shouldn't matter to the player whether his cards are dealt face-down or face-up since the dealer must play according to predetermined rules. If the dealer has less than 17, she must hit. If the dealer has 17 or more, she must stand (take no more cards), unless it is a "soft 17" (a hand that includes an ace valued as "11," for example a hand consisting of Ace+6, or Ace+2+4). With a soft 17, the dealer follows the casino rules printed on the blackjack table, either to "hit soft 17" or to "stand on all 17's."

The highest possible hand is a "blackjack" or "natural," meaning an initial two-card total of 21 (an ace and a ten-value card). A player blackjack is an automatic winner unless the dealer also has blackjack, in which case the hand is a "push" (a tie). When the dealer upcard is an ace, the player is allowed to make a side bet called "insurance," supposedly to guard against the risk that the dealer has a blackjack (i.e., a ten-value card as her hole card). The insurance bet pays 2-to-1 if the dealer has a blackjack. Whenever the dealer has a blackjack, she wins against all player hands except those that also have a blackjack (which are a "push").

The minimum and maximum bets are posted on the table. The payoff on most bets is 1:1, meaning that the player wins the same amount as he bets. The payoff for a player blackjack is 3:2, meaning that the casino pays $3 for each $2 originally bet. (There are some single-deck games which pay only 6:5 for a blackjack.)

Player decisions
After receiving his initial two cards, the player has four standard options: he can "Hit," "Stand," "Double Down," or "Split a pair." Each option requires the use of a hand signal. At some casinos or tables, the player may have a fifth option called "Surrender." signal: (handheld) scrape cards against table; (face up) touch finger to table signal: (handheld) slide cards under bet; (face up) move hand horizontally signal: place additional chips next to (not on top of) original bet, make "one finger" sign signal: place additional chips next to (not on top of) original bet, make "two fingers" sign signal: There is no commonly accepted hand signal; it is just done verbally.
 * Hit: Take another card.
 * Stand: Take no more cards, also "stick" or "stay".
 * Double down: On his first two cards, the player may "double down," i.e., "double" his bet and receive only one card face "down." To do this he moves a second bet equal to the first into the betting box next to his original bet. (If desired, the player is usually allowed to "double down for less," although this is not a good idea.)
 * Split a pair: If his first two cards are a "pair," meaning two cards of the same value, the player can "split the pair." To do this, he moves a second bet equal to the first into the betting box next to his original bet. The dealer splits the cards to create two hands, placing one bet with each hand. The player then plays two separate hands.
 * Surrender: Some casinos offer a fifth option called "Surrender." After the dealer has checked for blackjack, the player may "surrender" by giving up half his bet and not playing out the hand.

The reason for requiring hand signals is to assist the "eye in the sky," a person or video camera located above the table but concealed behind one-way glass. It is used in order to protect the casino against dealers or players who cheat. (It may also be used to protect the casino against card-counters, even though card-counting is not illegal.)

The player can take as many hits as he wants (except on a "double down"). However, if he busts, he loses that hand. After all the players have finished making their decisions, the dealer then reveals her hole card and plays out her hand according to predetermined rules.

Rule variations and the "house advantage"
The blackjack player will encounter many rule variations which affect the house advantage and therefore affect his chances of winning. Some rules are determined by law or regulation, others by the casino itself. Not all rules are posted, so the player may have to ask either beforehand or when the situation occurs. Over 100 variations exist.

The casino has a "house advantage" at blackjack just as it does at any other casino game. If a particular casino game has a house advantage of 5%, it means that - over the long run - the casino will win about 5% of any initial bet. As long as the blackjack player uses the best possible strategy (a strategy which is known as "Basic Strategy"), the house advantage in blackjack is less than 1%. This is very favorable to the player compared to other casino games. Of course, many blackjack players do not know Basic Strategy or do not follow it, so the true house advantage in those cases is much higher.

Dealer hits soft 17?
Each casino has a rule about whether or not the dealer hits soft 17, a rule which is printed on the table itself. In the "S17" game, the dealer stands on all 17s. In the "H17" game, the dealer hits on soft 17s. Of course, she always stands on hard 17s. In either case, the dealer has no choice; she either must or must not hit. The "Hit soft 17" game is substantially less favorable to the player with about a 0.2% higher house advantage.

Number of decks
The number of decks used has a major effect on the player's chance of winning, because it affects the house advantage. (See comparative statistics below.) All things being equal, fewer decks are more favorable for the player. (This is true for basic strategy players, even without card counting.) But all things are not equal; multi-deck games almost always have otherwise better rules than single-deck games. For illustrative purposes, the statistics below all use the same rules -- double after split, dealer hits soft 17.

House Advantage by Number of Decks (H17, DAS)

Single deck 0.04%

Double deck 0.49%

Four decks  0.59%

Six decks   0.66%

Eight decks 0.69%

Surrender
Some casinos offer a favorable option called "surrender," which allows the player to give up half his bet and not play out the hand. This option is sometimes referred to as "late" surrender because it occurs after the dealer has checked her hole card for a blackjack. (When casinos first opened in Atlantic City, the surrender option was available before the dealer checked for blackjack - a rule highly advantageous to the player - but this "early surrender" option soon disappeared.) Early Surrender variations still exist in several countries.

Resplit to nn
If the player splits a pair other than aces and a third card of that value appears, the player can usually resplit by putting up another bet equal to the original bet. Then there will be three bets on the table and three separate hands. Some casinos allow unlimited resplitting of cards other than aces, while others may limit it to a certain number of hands, such as four hands (for example, "resplit to 4").

Resplit aces
When the player's first two cards are two aces, the player may split them once. If a third ace appears, however, it cannot be resplit in most casinos. If resplitting aces is allowed, this is favorable to the player.

Double after split
After splitting a pair, some casinos allow the player to "double down" on each of the new two-card hands. This is called "double after split" (DAS) and provides an advantage to the player of about 0.12%.

Double on 10 or 11 only
Often called "Reno" rules, this rule restricts the player to doubling down only on an initial player total of 10 or 11 (sometimes 9, 10, or 11). It prevents doubling on soft hands such as soft 17 (ace-6), and is unfavorable for the player. It increases the house advantage by about 0.20%.

European no-hole-card rule
In some places, the dealer does not receive a hole card, but if the dealer is later found to have blackjack, the player loses only his original bet but not any additional bets (doubles or splits). This has the same advantage as the usual game, and as such does not change basic strategy.

Altered payout for blackjack
In some places, a blackjack pays only 6:5 or even 1:1 instead of the usual 3:2. This is the most unfavorable variation, increasing the house edge significantly more than any other player restriction.

Dealer wins ties
This is catastrophic to the player, though rarely used in standard Blackjack. It is sometimes seen in "blackjack-like" games.

Five card charlie/Five card trick
With this rule, the player always wins when five cards have been drawn without busting, unless there is a blackjack on the table.

Insurance
If the dealer's upcard is an ace, the player is offered the option of taking Insurance before the dealer checks her 'hole card'.

Insurance is a side bet of up to half the original bet placed on a special portion of the table usually marked "Insurance Pays 2 to 1". The idea is that if the dealer has a blackjack, i.e., a ten-value card as her hole card, then the player is usually going to suffer the loss of his original bet. By making an extra bet of half his original bet on "insurance," which pays 2-to-1 if the dealer has a blackjack, the "insurance proceeds" will supposedly make up for any loss on the original bet. Of course the insurance bet is forfeited if the dealer does not have blackjack, although the player can still win or lose on the original bet.

Insurance is a poor bet for the player unless he is counting cards, because the casino has a theoretical house advantage of 7.69% ("infinite deck"). The theoretical house advantage is easy to calculate, since the player is essentially betting that the dealer's hole card is a ten-value card. To calculate it, we can use the example of a player with an original bet of $20, the dealer has an ace, and the player takes insurance for $10. In an infinite deck, 4/13 of the cards are "tens" (10, J, Q, or K). In theory, the insurance bet will lose 9/13 of the time for minus $90 and will win 4/13 of the time for plus $80, giving a net loss of $10 for 13 hands. The average loss is $0.77 per hand ($10/13), or 7.69%. Therefore, taking insurance is a poor bet for the player (unless he is counting cards).

The odds on the Insurance bet are not improved if the player has a blackjack -- it's still a poor bet. Insurance is simply a side-bet that the dealer has a ten-value hole card, regardless of the player's original cards. We can use the same example, where the player has a blackjack on his original bet of $20, the dealer has an ace, and the player takes insurance for $10. The two bets are completely separate. The player can expect on average to win $20.77 for his blackjack, since the original bet wins 9/13 of the time for a total of $270 (9 x $30) and ties 4/13 of the time for a gain of zero, for an average gain of $20.77 per hand ($270/13). Meanwhile, the insurance side bet of $10 is calculated separately and loses $0.77 on average. Therefore, on average, the player would win $20.77 for his blackjack on his original bet, and would lose $0.77 on the $10 insurance bet, if he takes insurance. The insurance bet is still not worthwhile (unless, again, the player is counting cards).

A variation on this is that some casinos or dealers may offer the player what they call "even money" by offering to pay out the blackjack at 1:1 when the upcard is an ace. This is exactly the same as taking insurance, although the player does not have to put up the insurance bet. Again, the player's expectation for the "even money" option is $20.00, instead of an average of $20.77, so it's not a favorable bet (unless the player is counting cards).

In casinos where a hole card is dealt, a dealer who is showing a card with a value of Ace or 10 may slide the corner of her hole card over a small mirror or electronic sensor on the tabletop in order to check whether she has a blackjack. This practice minimizes the risk of inadvertently revealing the hole card, which may give the sharp-eyed player a considerable advantage.

Basic strategy
Because blackjack has an element of player choice, players can reduce casino advantage by playing optimally. The complete set of optimal plays is known as basic strategy. There are slight variations depending on the house rules and number of decks.   The above is a basic strategy table for 3 or more decks, dealer stands on soft 17, double on any 2 cards, double after split allowed, dealer peeks for blackjack, and blackjack pays 3:2. Key:
 * S = Stand
 * H = Hit
 * Dh = Double (if not allowed, then hit)
 * Ds = Double (if not allowed, then stand)
 * SP = Split
 * SU = Surrender (if not allowed, then hit)

Most Las Vegas strip casinos hit on soft 17. This rule change requires a slightly modified basic strategy table -- double on 11 vs A, double on A/7 vs 2, and double on A/8 vs 6. Most casinos outside of Vegas still stand on soft 17.

Card counting
Basic strategy provides the player with the optimal play for any blackjack situation based on millions of hands played in the long run. However in the short run, as the cards are dealt from the deck, the remaining deck is no longer complete. By keeping track of the cards that have already been played, it is possible to know when the cards remaining in the deck are advantageous for the player.

Card counting creates two opportunities:
 * The player can make larger bets when he has the advantage. For example, the player can increase the starting bet if there are many aces and tens left in the deck, in the hope of hitting a blackjack.
 * The player can use information about the remaining cards to improve upon the basic strategy rules for specific hands played. For example, with many tens left in the deck, the player may double down in more situations since there is a better chance of making a strong hand.

Virtually all card-counting systems do not require the player to remember which cards have been played. Rather, a point system is established for the cards, and the player keeps track of a simple point count as the cards are played out from the dealer.

Depending on the particular blackjack rules in a given casino, basic strategy reduces the house advantage to near 0 with some single-deck games, and less than 1% in a multi-deck game. Card-counting, if done correctly, can give the player an advantage, typically ranging from 0 to 2% over the house. To counter card-counting, many casinos switched from a single deck to multiple decks, with the cards dealt out of a container known as a "shoe".

In most US jurisdictions, card-counting is legal and is not considered cheating. However, most casinos have the right to ban players, with or without cause, and card-counting is frequently used as a justification to ban a player. Usually, the casino host will simply inform the player that he or she is no longer welcome to play at that casino. Players must be careful not to signal the fact that they are counting. The use of electronic or other counting devices is usually illegal.
 * See also: Martingale (betting system)
 * See also: MIT Blackjack Team

Composition-dependent strategy
Basic strategy is based on a player's point total and the dealer's visible card. A player's ideal decision may depend on the composition of his hand, not just the information considered in the basic strategy. For example, a player should ordinarily stand when holding 12 against a dealer 4. However, in a single deck game, the player should hit if his 12 consists of a 10 and a 2; this is because the player wants to receive any card other than a 10 if hitting, and the 10 in the player's hand is one less card available to cause a bust for the player or the dealer.

However, in situations where basic and composition-dependent strategy lead to different actions, the difference in expected value between the two decisions will be small. Additionally, as the number of decks used in a blackjack game rises, both the number of situations where composition determines the correct strategy and the house edge improvement from using a composition-dependent strategy will fall. Using a composition-dependent strategy only reduces house edge by 0.0031% in a six-deck game, less than one tenth the improvement in a single-deck game (0.0387%).

Shuffle tracking
Techniques other than card-counting can swing the advantage of casino blackjack towards the player. All such techniques are based on the value of the cards to the player and the casino, as originally conceived by Edward O. Thorp. One technique, mainly applicable in multi-deck games, involves tracking groups of cards (aka slugs, clumps, packs) during the play of the shoe, following them through the shuffle and then playing and betting accordingly when those cards come into play from the new shoe. This technique, which is admittedly much more difficult than straight card-counting and requires excellent eyesight and powers of visual estimation, has the additional benefit of fooling the casino people who are monitoring the player's actions and the count, since the shuffle tracker could be, at times, betting and/or playing opposite to how a straightforward card-counter would.

Arnold Snyder's articles in Blackjack Forum magazine brought shuffle tracking to the general public. His book, The Shuffle Tracker's Cookbook, mathematically analyzed the player edge available from shuffle tracking based on the actual size of the tracked slug. Jerry L. Patterson also developed and published a shuffle-tracking method for tracking favorable clumps of cards and cutting them into play and tracking unfavorable clumps of cards and cutting them out of play. Other legal methods of gaining a player advantage at blackjack include a wide variety of techniques for hole carding or gaining information about the next card to be dealt.

Variants
Pontoon is an English variation of blackjack with significant rule and strategy differences. However, in Australia and Malaysia, Pontoon is an unlicensed version of the American game Spanish 21 played without a hole card; despite the name, it bears no relation to English Pontoon.

Spanish 21 provides players with many liberal blackjack rules, such as doubling down any number of cards (with the option to 'rescue', or surrender only one wager to the house), payout bonuses for five or more card 21s, 6-7-8 21s, 7-7-7 21s, late surrender, and player blackjacks always winning and player 21s always winning, at the cost of having no 10 cards in the deck (though there are jacks, queens, and kings).

21st Century Blackjack (also known as "Vegas Style" Blackjack) is commonly found in many California card rooms. In this form of the game, a player bust does not always result in an automatic loss; there are a handful of situations where the player can still push if the dealer busts as well, provided that the dealer busts with a higher total.

Certain rule changes are employed to create new variant games. These changes, while attracting the novice player, actually increase the house edge in these games. Double Exposure Blackjack is a variant in which the dealer's cards are both face-up. This game increases house edge by paying even money on blackjacks and players losing ties. Double Attack Blackjack has very liberal blackjack rules and the option of increasing one's wager after seeing the dealer's up card. This game is dealt from a Spanish shoe, and blackjacks only pay even money.

The French and German variant "Vingt-et-un" (Twenty-one) and "Siebzehn und Vier" (Seventeen and Four) don't include splitting. An ace can only count as eleven, but two aces count as a Blackjack. This variant is seldom found in casinos, but is more common in private circles and barracks.

Chinese Blackjack is played by many in Asia, having no splitting of cards, but with other card combination regulations.

Another variant is Blackjack Switch, a version of blackjack in which a player is dealt two hands and is allowed to switch cards. For example, if the player is dealt 10-6 and 5-10, then the player can switch two cards to make hands of 10-10 and 6-5. Natural blackjacks are paid 1:1 instead of the standard 3:2, and a dealer 22 is a push.

In Multiple Action Blackjack the player places between 2 or 3 bets on a single hand. The dealer then gets a hand for each bet the player places on a hand. This essentially doubles the number of hands a single dealer can play per hour. Splitting and Doubling are still allowed.

Recently, thanks to the popularity of poker, Elimination Blackjack has gained a following. Elimination Blackjack is a tournament format of blackjack.

Many casinos offer optional side bets at standard blackjack tables. For example, one common side-bet is "Royal Match", in which the player is paid if his first two cards are in the same suit, and receives a higher payout if they are a suited queen and king (and a jackpot payout if both the player and the dealer have a suited queen-king hand). Another increasingly common variant is "21+3," in which the player's two cards and the dealer's up card form a three-card poker hand; players are paid 9 to 1 on a straight, flush or three of a kind. These side bets invariably offer worse odds than well-played blackjack.

In April 2007 a new version of Blackjack, called Three Card Blackjack was approved for play in the State of Washington. Three Card Blackjack is played with one deck of 52 cards. In Three Card Blackjack the players place an ante bet. The players and dealer are then dealt 3 cards each. The players make the best blackjack (21) hand they can using 2 or all 3 cards. If the player likes his hand he makes a play bet that is equivalent to the ante bet. The dealer must qualify with an 18 or better. If the dealer qualifies and the player beats the dealer, the player is paid 1-1 on both the Ante and Play bets. If the dealer does not qualify, the player is paid 1-1 on his Ante bet and Play bet pushes. There is no hitting and no busting. At the same time that the player makes the Ante bet, he has the option of making an Ace Plus bet. If the player has one Ace in his hand of 3 cards, he gets paid 1-1. An Ace and a 10 or Face Card pays 3-1. An Ace and two 10's or Face cards is paid 5-1. Two Aces pays 15-1. Three Aces pays 100-1.

Blackjack Hall of Fame
In 2002, professional gamblers around the world were invited to nominate great blackjack players for admission into the Blackjack Hall of Fame. Seven members were inducted in 2002, with new people inducted every year afterwards. The Hall of Fame is at the Barona Casino in San Diego, California. Members include Edward O. Thorp, author of the 1960s book Beat the Dealer which proved that the game could be beaten with a combination of basic strategy and card counting; Ken Uston, who popularized the concept of team play; Arnold Snyder, author and editor of the Blackjack Forum trade journal; Stanford Wong, author and popularizer of the "Wonging" technique of only playing at a positive count, and several others.