During the last annual conference of ECSITE (European Collaborative for Science and Technology Exhibitions; Helsinki, June 2005), for the first time two discussion sessions were devoted to explainers, the innumerable people – young students mainly – who welcome visitors at exhibitions, museums and festivals, who animate laboratories and science shows, who guide, explain and lately also stimulate and manage discussions and participatory procedures. Thanks to the involvement of the speakers, who agreed to submit a broadened version of their papers, JCOM is glad to host the proceedings of these meetings. A great deal has to be done yet in order to analyse the complex European context and to fully understand the explainer’s professional profile.