Participation encompasses a series of activities related to political life, aimed at influencing in a more or less direct - legal, conventional, pacific or contentious - way public decisions. Definitions can vary, depending on whether one focuses on individual or collective actors, on the social or institutional environment, or on the means and procedures of participation (Barnes and Kaase 1979).

On the horizontal axis, we see the shift from individuals to collective aggregates as discussed by the sociology of collective action. A single individual entitled with her own rights, personal means, resources, and identities (Milbrath 1965) is opposed to organized aggregates of people, which can count on organizational resources such as membership, finances, strategic position in the society or in the political system, know-how, better access to information and to channels of expression (Bentley 1908; Olson 1965; Almond and Powell 1966). On the vertical axis, the legislature represents the institutional arena legitimizing the existence of a democratic political system and, in turn, legitimized by the possibility of political participation. Civil society is the arena where economic and social conflicts are developed and then conveyed to the institutional sphere via various forms of participation.