This book on human computer communication is designed for final year Computer Science and Engineering students and technological aficionados. In sync with syllabi of institutions offering the subject, the book focuses on designing user-centric system software, incorporating the user behavior and mental models. It includes topics on basic software design process and its stages, role of computation in design, computational framework for design, and computational models of users and systems. All concepts, laws and challenges are validated with cases studies and practical examples. The book appraises reader with the state-of-the-art technological development, with the underlying theme that humans come first. \n\nSalient Features: \n\nDedicated chapter on recent trends in the user-centric systems \n\nIllustrative case studies on key concepts and various user-centric devices \n\nCovers new concepts, such as, ubiquitous area and wearable devices \n\nAddresses issues and challenges, both from the research and development perspective