2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/120551SO(10) grand unified theory seems to have all the ingredients to be a complete unified theory of quarks and leptons. I review here its minimal, possibly realistic versions, both supersymmetric and not.13 pages; talk given at the GustavoFest, Lisbon, 2004, published in the ProceedingsHigh Energy Physics - Phenomenologytext