This lecture by Marco Contalbrigo explores the investigation of hadron structure through deep-inelastic scattering experiments. Delve into the experimental methods and findings that help physicists understand the fundamental composition of hadrons, with particular focus on how deep-inelastic scattering has contributed to our knowledge of particle physics. The 46-minute presentation from the Galileo Galilei Institute (GGI) covers key concepts in hadron structure research and experimental techniques used to probe the internal dynamics of these subatomic particles.