A reaction is autocatalytic when a product (or a later intermediate) catalyzes its own formation, so that the observed rate increases with conversion until the substrate is depleted. The catalytic species is generated by the same stoichiometric transformation that it accelerates, producing a kinetic signature of a lag phase followed by acceleration. Mechanistically, autocatalysis may involve direct catalysis by the product, a product-assisted pre-equilibrium, or a closed cycle in which an intermediate is regenerated with net formation of product ^[1]. Nonlinear autocatalysis coupled to recycling can amplify a minute enantiomeric excess to complete chiral purity during crystallization, illustrating the kinetic consequence of a product-dependent rate law ^[2]. In molecular organic reactions, autocatalysis appears in protodeboronation pH–rate profiles and in related disproportionation manifolds where a product or byproduct participates in the rate-determining step ^[3]. The concept is a kinetic and mechanistic category, not a named reagent class: any transformation whose rate law contains a positive power of a product concentration is autocatalytic, whether the chemistry is organic, inorganic, or crystallization-based ^[1].