2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/41452Data on solar and atmospheric neutrinos provide evidence for neutrino masses and mixings. We review some basic neutrino properties, the status of neutrino oscillations and implications for grand unified theories, including leptogenesis.54 pages, 26 figures, Lectures given at the 2001 European School of High-Energy Physics, Beatenberg, Switzerland; typos corrected, reference addedHigh Energy Physics - PhenomenologyAstrophysicsHigh Energy Physics - ExperimentHigh Energy Physics - Theorytext