Citizen participation is considered as one of the core elements of transparency of Governments with regard to their citizens. In these participations, Governments generally ask people to give their opinions with regard to particular subjects. Governments then consider these opinions in their decision-making process. With the emergence of new ICTs that are widely spread and used by citizens, Government made a shift from face-to-face citizens' participation to an electronic citizens' participation or the so-called e-participation. In this context, governments need to identify the best means to achieve electronic participation in a way and a time that gives the citizens the opportunity to have a real influence on the decisions to be made. However, the literature shows that there is no consensus about these means. This paper is an attempt to examine, through an extensive literature review, the current state of the art about e-Participation. Results show that social welfare is the dominant domain in which e-Participation was conducted. They show also that social media technologies are the most used to conduct e-Participation initiatives.