Palming A Card
The magician hides a card in is palm so that it is not visible to the spectator who only sees the back of the magicians hand.
How It's Done
Place the card in your palm and put pressure against the upper left of the card with your pinky, and the lower right of the card with your palm next to your thumb. You should be able to have your hand close to open so that it does not appear as though you are holding a card.