2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/57709Dyson's (1962) classification of matrix ensembles is reviewed from a modern perspective, and its recent extension to disordered fermion problems is motivated and described. It is explained in particular why symmetry classes are associated with large families of symmetric spaces.Short review article (max. 4000 words) solicited by the editors of the Encylopedia of Mathematical Physics (Elsevier, 2005)Mathematical Physicstext