2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/39484This is a brief review of the present status, of some recent developments and of the open challenges in string/M theory.Latex file, 11 pages, 6 figures. Plenary talk at the EPS HEP99 Conference, Tampere, FinlandHigh Energy Physics - Phenomenologytext