Book excerpt: Dynamic light scattering (DLS) is an important concept that has found applications in the characterization of the biophysical properties of materials for a wide range of applications. DLS studies are extensively employed in material science and engineering to evaluate particle size distribution and surface charge for applications in nanomaterial synthesis, biomolecular analysis, pharmaceutical development and environmental applications. The aim of this book is to provide an overview of research advances relating to the principle and applications of DLS in various fields. The book is divided into two parts Part 1 discusses the uses of DLS in material science and engineering applications and Part 2 focuses on applications of DLS in biological sciences. Chapter 1 aims to provide an overview of the working principle, mathematical models and different types of DLS analysis methods. In addition, recent trends in DLS studies and applications in various fields are also discussed. Chapter 2 discusses the uses of DLS for nanomaterial characterization in terms of the size, size distribution and zeta potential of particles. Chapter 3 compares two techniques (DLS and SAXS) and provides evidence that nanocatalyst can be characterized more effectively by modifying DLS with SAXS. In Chapter 4 the authors demonstrate the application of DLS in characterizing self-assembling and stimuli-responsive di-block copolymers in aqueous media and their association with low molecular weight drugs. Chapter 5 discusses slow and ultraslow dynamics, probed by DLS measurements, in common organic molecular liquids, ionic liquids (ILs), aqueous solutions of salts and molecular solids and liquid-liquid binary mixtures.