The dynamics of liquids play a major role in many chemical, physical, and biological processes. However, the strong intermolecular interactions and high degree of disorder that characterize liquids pose a significant challenge to developing a detailed understanding of this state of matter. The chapters of this book describe current research using state-of-the-art techniques in experiment, simulation, and theory to unravel the mysteries of liquid behaviour. Sections of the book are devoted to microscopic dynamics, photochemistry, vibrational dynamics, water, metastable liquids, and confined liquids. The introduction includes a detailed background discussion of terminology, major problems, and leading approaches in the context of these different topic areas.