A tangible user interface (TUI) is a user interface in which a person interacts with digital information through the physical environment. The initial name was Graspable User Interface, which is no longer used. The purpose of TUI development is to empower collaboration, learning, and design by giving physical forms to digital information, thus taking advantage of the human ability to grasp and manipulate physical objects and materials. One of the pioneers in tangible user interfaces is Hiroshi Ishii, a professor at the MIT who heads the Tangible Media Group at the MIT Media Lab. His particular vision for tangible UIs, called Tangible Bits, is to give physical form to digital information, making bits directly manipulable and perceptible. Tangible bits pursues the seamless coupling between physical objects and virtual data. Characteristics Physical representations are computationally coupled to underlying digital information. Physical representations embody mechanisms for interactive control. Physical representations are perceptually coupled to actively mediated digital representations. Physical state of tangibles embodies key aspects of the digital state of a system According to Mi Jeong Kim and Mary Lou Maher, the five basic defining properties of tangible user interfaces are as follows: space-multiplex both input and output; concurrent access and manipulation of interface components; strong specific devices; spatially aware computational devices; spatial re-configurability of devices. Differences: Tangible and Graphical user interface A Tangible user interface must be differentiated by a Graphical user interface (GUI). A Graphical User Interface exists only in the digital world where as the TUI connects the digital with the physical world. For example a screen displays the digital information, where as a mouse allows us to directly interact with this digital information. Moreover a Tangible user interface also represents the input in the physical world, unlike the Graphical user interface, and makes the digital information directly graspable. A Tangible user interface is usually built for one specific target group, because of the low range of possible application areas. Therefore, the design of the interface must be developed together with the target group to ensure a good user experience. In comparison with a TUI, the Graphical user interface has a wide range of usages in one interface. Because of that it targets a large group of possible users. One advantage of the Tangible user interface is the user experience, because it occurs a physical interaction between the user and the interface itself (E.g.: SandScape: Building your own landscape