Card counting  Card counting is a casino card game strategy used primarily in the blackjack family of casino games to determine whether the next hand is likely to give a probable advantage to the player or to the dealer. Card counters are a class of advantage players, who attempt to decrease the inherent casino house edge by keeping a running tally of all high and low valued cards seen by the player. Card counting allows players to bet more with less risk when the count gives an advantage as well as minimize losses during an unfavorable count. Card counting also provides the ability to alter playing decisions based on the composition of remaining cards. Card counting, also referred to as card reading, often refers to obtaining a sufficient count on the number, distribution and high-card location of cards in trick-taking games such as contract bridge or spades to optimize the winning of tricks. The most common variations of card counting in blackjack are based on statistical evidence that high cards (especially aces and 10s, and to a lesser extent 9s) benefit the player more than the dealer, while the low cards, (3s, 4s, 6s, and especially 5s, and to a lesser extent 2s and 7s) help the dealer while hurting the player. Higher concentration of high cards benefit the player in the following ways:   Contrary to the popular myth, card counters do not need unusual mental abilities to count cards, because they are not tracking and memorizing specific cards. Instead, card counters assign a point score to each card they see that estimates the value of that card, and then they track the sum of these values – a process called keeping a "running count." The myth that counters keep track of every card was portrayed in the 1988 film "Rain Man", in which the savant character Raymond Babbitt counts through six decks with ease and a casino employee erroneously comments that it is impossible to count six decks. Basic card counting assigns a positive, negative, or zero value to each card value available. When a card of that value is dealt, the count is adjusted by that card's counting value. Low cards increase the count as they increase the percentage of high cards in the remaining set of cards, while high cards decrease it for the opposite reason. For instance, the Hi-Lo system subtracts one for each dealt 10, Jack, Queen, King or Ace, and adds one for any value 2-6. Values 7-9 are assigned a value of zero and therefore do not affect the count. The goal of a card counting system is to assign point values that roughly correlate to a card's Effect of Removal (EOR).