Active Galactic Nuclei are powered by accretion of matter onto the supermassive black holes that reside in the centres of most galaxies. Black holes in this growing phase can output sufficient energy and momentum to affect large regions of their host galaxy and even the medium within their galaxy group or cluster, even though the central engine is comparatively tiny. The accretion process is extremely efficient in releasing the gravitational potential energy of the surrounding gas, making the accretion disc around the black hole shine brightly over a wide range of wavelengths. This disc, coupled to other structures in the central engine --- X-ray corona, dusty torus and jet --- emit or reprocess emission over the entire observable electromagnetic spectrum. Excepting the jet, the entire central engine is too small to resolve directly, so the accretion process has to be studied indirectly through its spectrum and flux variability.
AGN research at UV focuses on the observational study of the accretion disc/X-ray corona/dusty torus system through IR, optical and X-ray data. We use spectral and variability information to reconstruct the principal components of the central engine and the relation between them.