Human Computer Interaction attracts innovation and creativity because of its multi-disciplinary nature, in computing and IT research and development. For the last 25 years or so, it inspired new solutions, specially, for the benefit of the user as a human being, making the user the focal point which technology should serve rather than the other way round. The Encyclopedia of Human Computer Interaction covers a wide range of HCI related topics, which cover various aspects such as: background information, basic concepts, review articles, challenges, case studies, new advances and inventions, different applications, and real life experiences stressing on lessons learnt, advantages and disadvantages, and HCI in and for every day life (which does not necessarily include technology).