On the whole, this dissertation presents its findings through a first-person perspective. From time to time, however, the pronoun "we" is used to emphasize the collaborative effort that went into particular parts of the research (see Chapter 2, Chapter 4 and Chapter 5). Introduction | 15 approach adopted in this dissertation (Section 1.6), and a short summary of the dissertation's contributions (Section 1.7). 1.2 Social movements, collective action and social media: The state of the art 1.2.1 Defining social movements and positioning individuals and organizations within social movements The study of social movements has a longstanding tradition in sociology that dates back to Durkheim's (1912) concept of "collective effervescence" and the Marxian heritage of Habermas (1979, 1987), Touraine (1981), and Calhoun (1982) (for a review of social movements in social theory, see Eder, 2015). Social movement studies are recognized as a scientific, "organizational" (DiMaggio & Powell, 1983) field of investigation and theorizing (Della Porta & Diani, 2015). Nonetheless, the study of social movements has benefited from and expanded thanks to developments in other fields, such as political science, organization studies, and communication science (Della Porta & Diani, 2015). Consequently, the study of social movements is characterized by an interdisciplinary perspective that has produced a variety of definitions of what a social movement is, as well as theories, approaches, and methods to study social movements (for reviews, see, among others,