Technological advances miniaturization of embedded computing technology and wireless c-
munication together with the evolution of global networks like the Internet have brought the
vision of pervasive and ubiquitous computing to life: technology seamlessly woven into the
fabric of everyday life. Along with this development goes the need and challenge of int- faces
supporting an intuitive unobtrusive and distraction free interaction with such technolo- rich
environments. Considering the huge amount and ever growing number of a vast manifold of
heterogeneous small embedded or mobile devices shaping the pervasive computing la- scape
makes traditional explicit and attention based styles of interaction appear hopeless. To make
computing part of everyday life the interfacing must go beyond traditional explicit
interaction: pervasive computing system designs will have to - and are already successfully
attempting to - revert the principle of the user being in an active and attentive role to one
where technology is attentive and active. Interaction is becoming implicit. Implicit
interaction is based on two main concepts: perception and interpretation. Perc- tion concerns
gathering information about the environment and situations usually involving (technological)
sensors. Interpretation is the mechanism to understand the sensed data. C- ceptually
perception and interpretation when combined are described as situational context.
