2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/166087A notion of a coring extension is defined and it is related to the existence of an additive functor between comodule categories that factorises through forgetful functors. This correspondence between coring extensions and factorisable functors is illustrated by functors between categories of descent data. A category in which objects are corings and morphisms are coring extensions is also introduced.The statement of the main result, Theorem 2.6, is corrected. Readers who used Theorem 2.6 in its original form are strongly advised to see this revised versionRings and AlgebrasCategory Theory16W30text