The research on metals in their liquid state has been underestimated for a long time and the specific literature was scarce compared to those regarding solid metals. In the last twenty years, the situation has progressively changed and the matter has emerged as a fundamental area of investigation for physicists, metallurgists and materials scientists with consequent achievement of relevant results both on basic and applicative aspects. Today the description and the characterisation of molten metals and alloys is a wide and interdisciplinary topic and involves different approaches, from physics to technology, from processing to modelling. The book is structured in review and research papers and offers the state-of-the-art information on physics, technological properties, processing and modelling of physical and technological behaviour of liquid metals and alloys.