Informal settings are activities emerging from young people coping with their everyday lives in public spaces without being initiated or guided by adults and often also without being intended as participation by the young people themselves. Youth as a life phase has emerged in modernity parallel to the idea of democracy. Youth research has been concerned with the degree to which young people accept and reproduce this existing order. The attention to young people’s participation has increased since the end of the 20th century marked by policy acts of international organisations such as the UN Convention of the Rights of the Child or the European Commission’s White Paper ‘A New Impetus for European Youth’. At local level, hearings were held with experts and stakeholders as well as with young people to disseminate and validate the findings and to stimulate processes of policy making. The chapter also presents an overview of the key concepts discussed in this book.