Preface: Archives, Libraries, and Museums in Era of Participatory Social Web

International audienceIn some areas, the participatory and collaborative nature of Web 2.0 are blurring old boundaries and hierarchies between professionals and amateurs.Professions related to the creation and dissemination of content and knowledge seem to be particularly affected (publishers, artists, graphic designers, journalists, authors, singers, actors, and so on). A massive adoption of participatory web technologies by the general public has led to a reconfiguration and repositioning of professionals and of the stakeholders in many sectors.This special issue (volume 39, number 3/4) investigates the changes underway in cultural heritage institutions such as libraries, archives, museums that are confronted with the widespread use of Web 2.0 platforms and practices