Throughout the years many blackjack players have relied on the practice of card counting to keep track of the cards that were played. This is one of the most effective techniques when used in conjunction with basic strategy.  Playing based on basic strategy lowers the house advantage to about one percent. Using card counting in conjunction with basic casino game strategy lowers the house advantage even further. The card counting player can ascertain if the deck is rich in high cards or low cards, and can bet accordingly. Because of the effectiveness of this practice, casinos have taken many steps to guard against the practice.  Players cannot use any mechanical or computerized equipment at the blackjack table.  They may be thrown out of the casino or arrested.

The UK gambling player cannot sit at the table and keep a written record of the cards played because they too will be thrown out of the casino. The best the card counter can do is to count mentally and not be too obvious about it. Casinos are not favorably inclined toward card counters and have developed techniques to counter or defeat the effectiveness of card counting. Card counting is easiest and most effective when there is one deck used from beginning to end. Decks are now shuffled after every hand and there is multi deck play. They also use automatic shufflers. These techniques have basically made card counting a useless practice.  The player can still keep track of the cards played but not like before.