2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/136338We extend the notion of algebraic stack to an arbitrary subcanonical site C. If the topology on C is local on the target and satisfies descent for morphisms, we show that algebraic stacks are precisely those which are weakly equivalent to representable presheaves of groupoids whose domain map is a cover. This leads naturally to a definition of algebraic n-stacks. We also compare different sites naturally associated to a stack.12 pages, to appear in Proc. Amer. Math. SocAlgebraic TopologyCategory Theory55U10 (Primary); 18G55, 14A20 (Secondary)text