Every casino game, including blackjack, has an integral mathematical edge, usually referred to as the ‘house edge’, over a player in the long term. In blackjack, the house edge for the standard, six-deck version is 0.64% but, by applying basic blackjack strategy, a player can reduce the house edge to the point where it is almost negligible. Regardless of some minor – albeit often strategically important – rule variations, blackjack is essentially a mathematical game, with a fixed set of rules, a fixed number of cards in the deck(s) and, hence, only a finite number of possible card combinations. Nevertheless, every playing decision has a direct influence on the outcome of a hand.
Basic blackjack strategy is a set of rules, determined mathematically, which allow a player to make correct playing decisions, thereby maximising winnings and minimising losses. Of course, the only information available to a blackjack player is the cards in his/her hand and the card that the dealer is showing, known as the ‘upcard’. However, by reference to a blackjack strategy chart, or matrix, which shows all possible card combinations, a player can take the action that gives him/her the best chance, mathematically, of winning any hand. To allow for rule variations, such as the option to ‘double down’ – that is, to double your original bet in exchange for a single card – after splitting two cards of the same value, some of the actions in basic blackjack strategy are dependent upon house rules.