Human-Computer Interaction (HCI) technology plays a vital role in diverse fields such as education, industry, national policy and cultural development. This is true not only in developed countries but also in rapidly developing countries. HCI technology is not only a relatively new industry in its own right; it also plays a central role in the integration of most, if not all, areas of expertise, including newer technologies, established industries, research and development fields and cultural activities. The evolution of HCI can be viewed analytically using a basic model which consists of three elements: the human, the computer, and the interaction between the two. First, regarding the human, ease-of-use is making computers (or artifacts) accessible to more and more people, including the young, the elderly, the physically or visually handicapped. A new research view, universal usability (or universal design), is emerging. Second, the computer, which interacts with humans, has come a long way from the mainframe to the compact personal computer. Now the locus of computation is shifting from the PC to personal digital assistants (PDAs), tablet computers and electronic whiteboards. Wearable computers, which may be worn like watches, glasses, clothing, and the like, are also greatly changing the traditional image of computers. Third, the interaction between humans and computers has developed from batch processing, through command lines, and on to the WIMP GUI which manipulates objects displayed in a bit map display using pointing devices such as a mouse. In recent years pen-based input interfaces, voice input interfaces, and nonverbal user interfaces (body language user interfaces which use gesture or eye gaze input), have each been actively researched. The chapters in this book deal with ubiquitous computing, interaction strategies and usability.