This book is a practical guide for individuals responsible for creating products that are safe, effective, usable, and satisfying in the hands of the intended users. The contents are intended to reduce the number of use errors involving medical devices that have led to injuries and deaths. The book presents the strong connection between user interface requirements and risk management for medical devices and instructs readers how to develop specific requirements that are sufficiently comprehensive and detailed to produce good results - a user-friendly product that is likely to be used correctly. The book's tutorial content is complemented by many real-world examples of user interface requirements, including ones pertaining to an inhaler, automated external defibrillator, medical robot, and mobile app that a patient might use to manage her diabetes. The book is intended for people representing a variety of product development disciplines who have responsibility for producing safe, effective, usable, and satisfying medical devices, including those who are studying or working in human factors engineering, psychology, mechanical engineering, biomedical engineering, systems engineering, software programming, technical writing, industrial design, graphic design, and regulatory affairs.