In participatory design, participants (putative, potential or future) are invited to cooperate with designers, researchers and developers during an innovation process. Potentially, they participate during several stages of an innovation process: they participate during the initial exploration and problem definition both to help define the problem and to focus ideas for solution, and during development, they help evaluate proposed solutions.[5] Maarten Pieters and Stefanie Jansen describe co-design as part of a complete co-creation process, which refers to the "transparent process of value creation in ongoing, productive collaboration with, and supported by all relevant parties, with end-users playing a central role" and covers all stages of a development process.[6]