Blackjack Card Counting
Basic blackjack strategy assumes that all cards have equal probability of being drawn. However this is not true. As cards are used in the play they are placed in a discard tray and these cards cannot be dealt to the players. Hence by keeping track of the cards in the discard tray a player can keep track of the cards left in the shoe and calculate the true probabilities of given cards being dealt. The player can therefore adjust the strategy to his advantage. The process of keeping track of the cards in the discard tray is known as card counting.
Initially card counting was done through electronic devices in land casinos. The cards dealt were fed to the device using coded buttons. This device was hidden in the person of the player, often in the shoe where it could be operated by the toes. This device transmitted the information wirelessly to a processor that was manned by a person outside the casino. The processor immediately computed and displayed the optimal move. The outside person conveyed this move to the player through a small earphone concealed in the player's years. Casinos began to detect instances of card counting because certain players won abnormally large amounts. A lengthy court procedure followed and ultimately card counting through physical devices was declared illegal.
Blackjack players then shifted to mental card counting. This could not be as perfect as the electronic card counting because the human mind is incapable of remembering and processing the huge volume of information involved in the fraction of a minute available. Mental card counting techniques do not track individual cards. They classify cards as high cards and low cards and then keep track of the number of high and low cards in the discard tray. Certain techniques classify the cards into a greater number of groups. These give better results but are more difficult to execute. One of simplest card counting techniques is the Hi-Lo system. It assigns a value of +1 to cards from twos to sixes and a value of -1 to tens, picture cards and aces. And then keeps a running count as the cards are transferred to the discard tray. A high positive score implies that the remaining deck is rich in high cards. Blackjack players use this information by placing larger bets and doubling down more often because this situation offers them increased chances of winning. Land casinos have neutralized card counting significantly by resorting to early shuffling. The count becomes more useful when there are fewer cards left in the deck. Most land casinos shuffle decks and start afresh when only half the cards are used thus denying card counters any real advantage. Some players were able to trace the location of packets of high or low cards after shuffling from their position in the discard tray. This has led to the use of more advanced shufflers by the land casinos.
Unfortunately card counting does not work in online casinos because the deck is shuffled after every hand.