Recently, the digital architectures of interaction have also become, more than a new information architecture, a new ecology of dialogue and participation. In addition to the new forms of debate and interaction which are expressed far beyond the dynamics of modern public opinion, the digital networks have opened spaces of experimentation for new decision-making collaborative practices. In several areas, the creation of platforms and architectures of debate and deliberations is putting new questions about the technological possibility of overcoming the representative democracy. Finally, this new digital ecology has been changing social actions in everyday life. The book analyzes these phenomena both through a theoretical reflection (first part) and by some case studies (second part), as the result of the activities promoted by the Net-Activism International Research Network based on Atopos Lab in Universidade de São Paulo. At the Network join: Università degli Studi “Roma Tre”, Universidade Lusófona do Porto, Université de Lille 2, Fondation Maison des Sciences de l’Homme, Paris.