For more than thirty years, people have relied primarily on screen-based text and graphics to interact with
computers. Whether the screen is placed on a desk, held in one’s hand, worn on one’s head, or embedded in
the physical environment, the screen has cultivated a predominantly visual paradigm of human-computer
interaction. In this chapter, we discuss a growing space of interfaces in which physical objects play a central
role as both physical representations and controls for digital information. We present an interaction model
and key characteristics for such “tangible user interfaces,” and explore these characteristics in a number of
interface examples. This discussion supports a newly integrated view of both recent and previous work, and
points the way towards new kinds of computationally-mediated interfaces that more seamlessly weave together
the physical and digital worlds.