This volume has the dual purpose of providing the conceptual tools to critically address both the development of historical-artistic investigation methods and the increasingly urgent field of conservation and use of works of art. The prolusions dedicated to the history of art criticism and iconography and iconology refer to the first intention, which trace the fundamental lines of the development of these disciplinary areas and address the main problematic issues present in the contemporary debate. In the second part of the volume, the headwords relating to the history of art criticism are essentially, although not exclusively, dedicated to concepts, always grasped in their historical development, used to define, classify, understand and appreciate works of art. The lecture notes on Museology and Restoration, as well as the relative lemmas of the Dictionary refer to the second intention. The items of museology/museography describe the different types of museums and the related problems. The voices on restoration, written in close interconnection with the relative opening, address with critical but also operational acumen the methods of intervention, the materials that make up the work of art and the problems - which we could almost define epistemological - that have conditioned and they still condition evaluations on the choices to be made when intervening on a work of art.