Actually the coin remained in his left hand, dropping down into the palm from the extended fingers. His eyes and directed attention followed the moving, closed right hand, while his unobserved left hand slipped the coin into his coat pocket. Then, when the performer slowly opened his right hand, the coin had apparently vanished, and his left hand was empty also. The coin did not vanish because the hand is quicker than the eye. The hand is slicker, not quicker, than the vision of spectators.
Magic is successful because it is nine-tenths simple distraction.
Your attention is cleverly misdirected. It is your own brain that deceives you. You do not see with your eyes alone, but with your brain and mind, which sorts out the confusion of outlines and colors, and forms them into definite, understandable images. Because the mind has so very much to do with what is being observed, deception is made possible. Your mind is a censor.