International scientific conferences are consubstantial to modern science, technology and medicine. According to the Union of international associations, over 170,000 have taken place between 1851 and 2017. The routine of international conferencing has only been interrupted by major events such as the two World Wars or, more recently, the Covid-19 pandemic. Yet save for a few memorable events, the phenomenon of international conferencing has not been looked at in any systematic way. Drawing from the research carried out within a HERA-funded, collaborative project associating the universities of Uppsala, Maastricht, Birkbeck College and the Centre Koyré, we will highlight some of the forms, uses and functions of international conferences since the nineteenth century: as forums for consensus-building, for knowledge production and communication, as places where communities and internationalism are performed, and as important public spaces where scientific, technical and political concerns intersect. We also suggest that historical investigations such as ours can help put into perspective current soul-searching about the future of conferencing.