User interface and acceptance

User interfaces to appliances and technical solutions are key to developing solutionsfor people. These interfaces between the human and the machine enable exchange of data, information and, finally, the generation of knowledge. Interfaces. There are different constraints on interfaces depending on which criteria are applied: If one looks at interfaces from a security and safety perspective, they should be as narrow as possible – the surface area that is exposed to a potentially harmful influence. However, if one looks from a more human perspective, interfaces should be wide and robust, allowing for a variety of inputs leading to a desirable output. In the case of user interfaces, different diverse modalities also are important. This latter view is the one which will be adopted in this chapter primarily. We take a positive stance here: User interfaces should enable, not restrict. A user interface is a key ingredient in tools that address human needs and amplify human capabilities. Furthermore, a user interface helps converting what users potentially can do into what they want to do