Cooper's best-selling first book, "About Face: The Essentials of User Interface Design," was first published in 1995. In it, Cooper introduces a comprehensive set of practical design principles, essentially a taxonomy for software design. By the second edition, as the industry and profession evolved, “interface design” had become the more precise “interaction design.” The basic message of this book was directed at programmers: Do the right thing. Think about your users. The book is now in its fourth edition, entitled" About Face: The Essentials of Interaction Design", and is considered a foundation text for the professional interaction designer. Cooper introduced the ideas of software application posture such as a "sovereign posture" where an application uses most of the space and waits for user input or a "transient posture" for software that does not run or engage with the user all the time. With websites he discusses "informational" and "transactional" postures in "About Face".