Participatory Design or co-design is a research method that actively involves all stakeholders in the design process, potentially in every stage. This approach is used to ensure that the result meets their needs and is usable. It has become increasingly popular in recent years as designers recognize the importance of involving end-users (current, potential or future) in the innovation process.

Research indicates that UX designers are more likely to create innovative concepts and ideas when working within a co-design environment with others than they do when creating ideas on their own. This is because the end-users' participation not only helps in decision making but also generates new ideas.

Co-design requires the end-user's participation at each stage of an innovation process, including Discovery, Define, Development, and Testing. By involving end-users throughout these stages, UX designers can better understand cultural, societal, or usage scenarios encountered by their user.

Participatory Design is often used by trained UX designers who recognize the difficulties involved in understanding the needs of their users. By collaborating with end-users from various backgrounds, designers can create solutions that are tailored to meet the needs of a diverse group of people.

User researchers are increasingly using co-design to do research. To begin with, user researchers invite end-users to participate in focus groups, interviews, and surveys to gather information about their experience with a product or service. This information is then used to generate ideas for potential solutions.

During the design phase, user researchers collaborate with end-users and other stakeholders to co-create prototypes and test them for usability. These prototypes are continually refined based on feedback from end-users until a final product is developed.

The Participatory Design process also involves building relationships with end-users that last beyond the research project. User researchers may continue to engage with users over time through community events, workshops or other forms of engagement.

Overall, Participatory Design allows user researchers to create solutions that are tailored to meet the needs of their users. By involving users throughout the design process, it ensures that the final product is both usable and relevant to its intended audience.