Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. User experience design (UXD) is a subset of the field of experience design that pertains to the creation of the architecture and interaction models that affect user experience of a device or system. The scope of the field is directed at affecting "all aspects of the user's interaction with the product: how it is perceived, learned, and used." This field has its roots in human factors and ergonomics, a field that since the late 1940s has been focusing on the interaction between human users, machines and the contextual environments to design systems that address the user's experience. The term also has a more recent connection to user-centered design principles and also incorporates elements from similar user-centered design fields. As with the fields mentioned above, user experience design is a highly multi-disciplinary field, incorporating aspects of psychology, anthropology, sociology, computer science, graphic design, industrial design and cognitive science.