This book looks at why ethnographic approaches have been turned to in the design of computing devices for the workplace, for the home and elsewhere. It presents a history of ethnography, both as it was practiced before computer science picked it up and since, most especially in the CSCW and HCI domains. It examines, further, the various ethnographic or 'fieldwork' frameworks currently popular, explaining and examining what each claims and entails. The focus of the book throughout is on the practical relationship between theory and practice, a relationship that is often misunderstood yet fundamental to successful design. The book is illustrated with real examples from the authors' various experiences in academic and commercial settings, reporting on the use of ethnography before, during and after design innovation and implementation. The result is a book that provides the working knowledge necessary for using any kind of ethnographic approach in the design of computer technologies.