ABSTRACT
This chapter aims to take the exploration of the constitution and continuous transformation of online publics a step further by examining and theorizing publicness as a communicative process that follows specific trajectories. The chapter concentrates on the role of specific social media platforms in two episodes of public contention. The one concerns the Twitter communication in the year following the New Delhi gang rape, which sparked mass protests. The second case study focuses on the Egyptian Kullena Khaled Said Facebook Page, which became a vital stage for the expression of grievances about the Mubarak regime in the months leading up to the uprising. Social media platforms are characterized by specific "architectures of participation" that shape the relations of publicness constituted through them. Such architectures involve specific rules of engagement and communication, regulating who communicates with whom, as well as how such communication unfolds.
