Online activism, mutual support and information sharing between patients, more or less “spontaneous” mobilisations organised from the web (#MeToo, Meetup), the Internet is increasingly becoming a source of organising events and activities in the “offline” world and no longer as a “virtual” space on its own, or only powered from outside. The objective of the thesis is to analyse how participants articulate online and offline exchanges to develop people-to-people relationships and build a group activity satisfactorily. This will include studying the expectations and relationships of individuals who engage in an activity on the Internet and seeking to find an offline extension, examine whether online interpersonal relationships are impacted by the face-to-face transition, and whether online exchanges are renewed or disappear for the benefit of other modes of communication. These issues will be addressed from the study of online groups or communities (e.g. Facebook groups gathered around shared interests or problems, participants in self-help platforms like mesvoisins.fr) by combining qualitative analysis (interviews, analysis of communications) and quantitative analysis (questionnaires)