A discussion of the AdS/CFT correspondence in IIB supergravity is given in a superspace context. The main emphasis is on the properties of SCFT correlators on the boundary which are studied using harmonic superspace techniques. These techniques provide the easiest way of implementing the superconformal Ward identities. The Ward identities, together with analyticity, can be used to give a compelling argument in support of the non-renormalization theorems for two- and three-point functions, and to establish the triviality of extremal and next-to-extremal correlation functions. Further simplifications in other correlators are also implied. The OPE is also briefly discussed.