Welcome to the European Synchrotron and Free Electron Laser User Organisation ESUO, the European Synchrotron and Free Electron Laser User Organisation offers to represent all users of synchrotron and free electron-laser facilities in Europe. Such state-of-the-art facilities enable various kinds of experiments in fields ranging from physics through life sciences to cultural heritage to be conducted. At present, users from 32 European member states and European associated countries are represented by ESUO national delegates / representatives.