A sleight of hand move involving an object in which the object is hidden behind the back of an outstretched hand. A back palm is usually done with cards. (This is the secret behind all of the famous card-dropping magic tricks you see on television.)The card(s) are palmed by slightly bending the card lengthwise between index and middle finger, and ring and little finger.
If you practice enough, you should be able to hide the card smoothly, in about a quarter of a second. The trick is to get the card hidden quickly and at the same time to position the card correctly so that none of the two vital corners peek out from the back of your hand.
Here's how to do it:
- Get a card that is flexible and bendy; NOT a credit card. A plastic trump card is ideal, but any normal card will do.
- Hold the card flat with your thumb, your middle finger, and your ring finger so that the longer ends of the card are parallel with your fingers.
- Slide your middle finger and your ring finger inwards, towards your palm while keeping the thumb still. The card should not move, but the fingernail-side of your two fingers should be flat against the card.
- At the same time, curl your index finger and your pinky inwards, and grasp the corners of the card with the inside of your fingers.
- Align all of your fingers into a very loose fist. If done right, the two corners of the card near your hand should be bent towards each other.
- Open your palm, keeping all your fingers together. The card should stick to the back of your hand, held in place by your index and your ring finger. Look at your palm; The card should be hidden behind your hand. See those bits of card poking out between your fingers? If you practice enough, those bits will become nonexistent and your hand will effectively hide the card.
- Wash, rinse, repeat. Keep practicing until you can do the last four steps (not including this one!) without thinking, in a split second. Then you're halfway done.
The back palm is also combined with the front palm to give the full illusion of an empty hand. In essence, the front palm is reverse of a back palm; the card is hidden inside the palm, as to be able to show the empty back of the hand.
With the back palm (and the front palm), you can do any variety of tricks. Improvise. Perhaps you could make a card vanish behind a person, and find it in the air, or you could also use it to reveal a previously forced card. The back palm is one of the tricks that is greatly versatile-- if, and only if you can pull it off perfectly. Watch out for angles at which spectators can see your card, and practice in front of mirrors. When you're performing the trick for a spectator, make sure that your back is just slightly turned that you can see the trick itself; otherwise, you run the risk of both looking awkward with your arm fully extended and also of being caught with the palmed card.
References: my own skill
Images: http://203.120.90.137/~guezs/magic/back_palming_a_card.htm