Natural bundles and natural liftings Prolongations of geometric structures Jacek Gancarzewicz W\l odzimierz Mikulski Zdzis\l aw Pogoda Abstract. This paper is a survey of results on prolongation functors, natural bundles and liftings of geometric structures. The general ideas, important examples and fundamental results in theory of natural bundles, product preserving functors, natural transformations and liftings of geometric objects are presented. Especially problems of regularity conditions and finite order for these notions are studied. There are also new results. Keywords: natural bundle, prolongation functor, product preserving functor, Weil functor, local algebra, geometric object, natural transformation, lifting, lift, order of natural bundle, order of transformation (of lift). AMS classifications: 53-02, 53C15, 58A20, 58A30.