Edge sorting is a technique used in advantage gambling where a player determines whether a face-down playing card is likely to be low or high at casino table games by observing and exploiting subtle unintentional differences on the backs of some types of card, after persuading a croupier to cooperate by unwittingly sorting the cards into low and high. Many packs of cards produced by manufacturers have unintentional edge irregularities. Typically all the backs of the cards in such a pack are identical, but the two long edges of each card are consistently distinguishable: the pattern is not symmetrical to a 180° rotation (half a full turn). During the course of a game, a player will ask the dealer, a casino employee, to rotate some face-up cards, perhaps saying they feel it will bring them l