As more and more research on involving users in design was published, the heterogeneity of design principles, methodologies and tools increased, leading to a variety of new terms being used to distinguish between the different types of solutions on how to support designers. Recently emerged research on human-centered or participatory design leads to small-scale differentiation, ending up in fuzziness. Influences from various disciplines form a conceptual landscape, in which the analytical boundaries become blurred and the conditions of certain design principles are characterized more by soft characteristics than systematic specifications. Consequently, practitioners feel challenged by the need of selecting the best suitable method for involving users into specific design tasks. Additionally, the term 'method' is perceived differently and in quite flexible ways. Hereby, the relationship between methods, tools and design methodologies is not taken into considerations. By analyzing the different methodological approaches of user-centered development practice, this paper reveals that not only the exchange between academia and practice, but also between different research communities lacks a consistent communication basis. To overcome this gap, a clarification of the essential terms necessary for describing the different methodological concepts related to user involvement is necessary. A first proposal towards a collection of these terms is given.
