2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/42367I review the role played by baryon and lepton numbers and their discrete subgroups in determining the low energy effective theory relevant for TeV physics.Based on the plenary talk given at SUSY'01, Dubna, Russia, and the talk given at Gran Sasso Extended Workshop on Astroparticle Physics, July 2002High Energy Physics - Phenomenologytext