Bottom dealing or "base dealing" is a sleight of hand

Sleight of hand

Sleight of hand, also known as prestidigitation or legerdemain, is the set of techniques used by a magician to manipulate objects such as cards and coins secretly....

 technique in which the bottom card from a deck of playing cards is dealt instead of the top card. It is used in card illusions, and as a method of card sharp

Card sharp

A card sharp is a person who uses skill and deception to win at poker or other card games...

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The deck is typically held in a modified mechanic's grip

Mechanic's Grip

The Mechanic's Grip is one of many ways to comfortably hold a deck of cards. The mechanic's grip is a standard grip utilized primarily by magicians and card cheaters as it allows a sturdy and versatile means by which to hold the cards...

 in the dealer's non-dominant hand. The dealer slides the top card partially off the deck as if to deal it, while the dominant hand instead takes hold of the bottom card. The card is snapped away from the deck while the top card is reset.

Unless the dealer is particularly skilled at bottom dealing, the technique produces a slightly different sound from standard dealing, and the second-to-bottom card may be drawn slightly out of place. This is called a "hanger."

Bottom dealing and second dealing

Second dealing

Second dealing is a method of manipulating a deck of cards during a card game by way of dealing the second, rather than the top, card of the deck, usually for the purpose of cheating...

 both have application in performance magic

Magic (illusion)

Magic is a performing art that entertains audiences by staging tricks or creating illusions of seemingly impossible or supernatural feats using natural means...

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Bottom dealing experts include Steve Forte, Jason England, Darwin Ortiz, and Richard Turner.