2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/55447This is an introduction to orientifolds with emphasis on applications to duality. Based on lectures given at the 1997 Trieste Summer School on Particle Physics and Cosmology, Italy.64 pages, LaTeX, 13 epsf figuresHigh Energy Physics - Theorytext