In these lectures moduli dependent charges, e. g. central charges, are analysed for generic N-extended supergravities in dimensions 4 =< D < 10 and p-extended objects.We derive central charge relations and study the extremization of the ADM mass per unit of p-volume of BPSp -extended objects.The existence of a topological formula for the Bekenstein-Hawking entropy is connected with group theoretical properties of the underlying duality symmetry.