Tangible interaction, or [Tangible User Interface] (TUI), in an approach to interaction that allows a user to interact with digital information through their physical environment. Tangible interaction was first defined in 1992, when Durrell Bishop created the Marble Answering Machine (1), in which a marble was used to represent a message on a telephone answering machine. Dropping the marble back into the dish would replay the message or return the call. Since then, tangible interaction has evolved to include new interfaces, including "smart objects" which are physical objects that have been embedded with sensors that collect information associated with interaction and link it with the associated application (2).