The work establishes a departure point for HCI researchers to explore the rich opportunities offered by multi-touch interaction. The viability of multi-touch interaction as a technique in HCI is outlined by discussing the role of touch surfaces from the perspective of current trends in HCI such as experiential design and user-centric approaches, as well as by drawing a link to established theoretical frameworks such as activity theory. A summary of the state of the art of multi-touch research is presented with a focus both on aspects of hardware sensor and software technology as well as...