X-rays are produced in the central region of Active Galactive Nuclei, within a few gravitational radii from the supermassive black hole. A fraction of this radiation then interacts with the accretion disk and the circumnuclear material. X-ray imaging and spectroscopy therefore provide information on the primary emitting "corona", on the structure and physical conditions in the accretion disk, on the space-time metrics around the black hole, on the size, shape and composition of the broad line region and the circumnuclear "torus". Disentangling all these components is the main challenge for X-ray AGN astronomy, and the key to obtain a complete view of the structure and the physical processes in the central regions of AGN.