Prototypes have acquired much prominence and visibility in recent times. Software development is perhaps the case in point, where the release of non-stable versions of programmes (beta versions) has become commonplace, as is famously the case in free and open source software. Prototyping has also become an important currency of explanation and description in art-technology contexts, where the emphasis is on the productive and processual aspects of experimentation: Medialabs, hacklabs, community and social art collectives, dorkbots, open collaborative websites or design thinking workshops are spaces and sites where prototyping and experimentation have taken hold as both modes of knowledge-production and cultural and sociological styles of exchange and interaction. Experimentation has also been at the centre of recent reassessments of the organisation of laboratory, expert and more generally epistemic cultures in the sciences. An interesting development is the shift in emphasis from the experimental as a knowledge-site to the experimental as a social process. This book brings some of the leading scholars in the fields of anthropology, social studies of science and technology, and critical design thinking, in a theoretical and ethnographic dialogue to explore the affordances of the `prototype' as a figure of our contemporary. This book was originally published as a special issue of the Journal of Cultural Economy.