Often confined in a commemorative or traumatic register, the concept of memory is not very present in research in information science and media studies. This work aims at showing that the memory question is however one of the major stakes of the networks age society. The reflection is based initially on an analysis of the evolution of images mediologic statute, whose entry in the digital environment modifies cultural balance and installs the supremacy of a logic of traces. In a second time, this logics is examined through the processes of mediation which it implements. Because of the traditional intercessors discredit, many saw in the influence of ICT a phenomenon of desintermediation. Our thesis is that the immediation rather concerns an ideological project : under the effect of information personalization and "socialization" of Internet, the mediation on which the collective is based did not disappear, it has been mouldd in identity mediation.   The prevalence granted to traces and identity makes traceability the paradigm of the new informational ecology, which we call hypersphere. Founding a " memory by default " where data and individuals are filed and calculated, traceability threatens as well individual freedom as the maintenance of public space. Beyond the protection measures, we propose to think about the conditions of traces reappropriation and restoration of confidence. The promotion of a more conscious digital presence and construction of memory projects - ordinary or institutional - are the ways which we explore.
