European perspectives for electron-nucleon scattering at the luminosity frontier

European perspectives are discussed on fixed-target electron or positron scattering experiments using polarized and unpolarized beams and targets in various combinations. The goal envisioned is a deep and complete understanding of the momentum and spin structure of hadrons in the context of Quantum Chromo Dynamics, based on measurements at moderate and low photon virtualities. This program can be realized by performing electron-nucleon experiments with high resolution and high luminosity, at beam energies of at least 25-30 GeV