Nanomaterials (nanostructures organized at the nanoscale) are present in many fields of application, from health, electronics, building materials, biological, bio-inspired or bio-sourced natural materials, energy conversion, to future quantum technologies. Whether it is to understand and improve their properties of use, to develop more sustainable processes of elaboration, to develop the new materials of tomorrow, more integrable, multifunctional and eco-responsible, the science of materials becomes more and more complex. To meet most of the industrial and societal challenges, and therefore scientific in the field, it is necessary to understand the physical and chemical mechanisms that govern the properties of materials at atomic or molecular scales, which allows electron microscopy. These techniques must also be coupled with new in situ and operando analysis methodologies in order to monitor the evolution of nanomaterials during their development and under conditions of use. Here again, the developments of recent years in electron microscopy, in particular at the Institute of Physics and Chemistry of Materials in Strasbourg (IPCMS), show the relevance of this technique which can still benefit from technical advances implemented on the most recent equipment.