Interaction Design is the design of systems in which people and artifacts engage with each other. It applies to the design of any virtual or physical instrument (usually computer-based) that facilitates interaction between people and people, or between people and devices or services. The field is ad hoc and multidisciplinary, so claims no 'unified theory'. Instead, in essays by 26 major thinkers and designers, "Theories and Practice in Interaction Design" presents the rich mosaic of ideas which nourish the lively art of interaction design. The editors' introduction is a critical survey of interaction design with a debt and contribution to neighbouring disciplines, notably cognitive psychology, computer science, discourse analysis, economics, engineering, linguistics, philosophy, psychology, semiotics and sociology.Twenty-two essays then follow, by experts in these disciplines and in interaction design, grouped under key terms: activity, emotion, situatedness, community, and so on. This book is of interest to anyone in the fields of Human-Computer Interaction, cognitive psychology, human factors/ergonomics, linguistics, semiotics, art, design, and computer science.