What Is It That Makes Participation in Design Participatory Design?

Despite renewed enthusiasm for participatory design it continues to be appropriate to question how it is conceived. Given the plurality and diversity of participatory design, and of the different communities in which it is applied, what is it that makes it participatory design rather than
something else? What are the common themes, characteristics and qualities that connect across different applications of participatory design. The purpose of this editorial therefore is to map a common ground from which to discuss participatory design matters across the different domains in which it is applied.