Abstract Context Prototyping is an established practice within product and user interface design that is also used as a requirements engineering (RE) practice within agile development. Even so, there is a lack of theory on prototyping. Aims Our main research objective is to support practitioners in improving on their prototyping practices. Method We have designed a model that describes key aspects of the practice of prototyping. The model is based on a systematic mapping study consisting of thirty-three primary studies and on empirical data from twelve case companies. We validate and demonstrate the applicability of our model through a focus group at one company and through semi-structured interviews at eleven (other) startup companies. Results Our prototyping aspects model (PAM) consists of five aspects of prototyping, namely purpose, prototype scope, prototype media, prototype use, and exploration strategy. This model has enabled practitioners to discuss their prototyping practices in terms of the concepts provided by our model. Conclusions The model can be used to categorise prototyping instances and can thereby support practitioners in reflecting and improving on their prototyping practices.

Background: Prototyping is an established practice for user interface design and for requirements engineering within agile software development, even so there is a lack of theory on prototyping. Aims: The main research objective is to provide a means to categorise prototyping instances, in order to enable comparison and reflection of prototyping practices. Method: We have performed a systematic mapping study of methodological aspects of prototyping consisting of thirty-three primary studies upon which we designed a model of prototyping that was validated through a focus group at a case company. Results: Our model consists of four aspects of prototyping, namely purpose, prototype scope, prototype use, and exploration strategy. This model supported the focus group participants in discussing prototyping practices by considering concrete prototyping instances in terms of the concepts provided by our model. Conclusions: The model can be used to categorise prototyping instances and can support practitioners in reflecting on their prototyping practices. Our study provides a starting point for further research on prototyping and into how the practice can be applied more cost-effectively to elicit, validate, and communicate requirements.