Card Counting

A strategy for getting the edge at blackjack by tracking the ratio of high cards to low cards that have already been played. A card counter raises his bet when the deck offers favorable odds to the player, and lowers his bet when the deck offers less-than-favorable odds to the player. There are multiple card counting systems with varying degrees of efficiency.

Keeping an eye on which cards have been played since the shuffle.

Recording (in memory) played cards (usually high cards) so as to establish a conditional probability advantage on the remaining cards against the dealer.