TALES supervisors Drs. Maurizio Paolillo and Iossif Papadakis publish new review article on AGN variability in the journal La Rivista del Nuovo Cimento of the Italian Physics Society. The review focuses on the observational properties of AGN variability in the ultraviolet, optical and X-ray spectral bands and their dependence on the AGN physical parameters such as black hole mass, luminosity and accretion rate. Opportunities and challenges offered by current and next-generation optical/X-ray surveys to use variability as an effective tool to study the growth of super massive black holes in the Universe are also discussed.