Crystallization is certainly among the most studied processes n science and also of great practical importance. Not only does it create beautiful objects of esthetic value, but the properties of many solid bodies and materials depend on their crystal structure, the crystal shape, and their mutual texture. Over many years, a classical picture of crystallization has been established that describes crystallization as a layer-wise deposition of atoms/ions/molecules on the surfaces of a crystal nucleus. However, it is well known that this classical model does not apply for many "real-life" crystallization processes. Thus, the comprehensive treatment of classical and nonclassical crystallization in this book will help catalyze progress in the field since it identifies mechanisms on the basis of their typical features and by using suitable analytical techniques. The book gives an introduction to self-assembly, classical crystallization, colloidal crystals, and mesocrystals. The principles of crystallization are described with examples, and nonclassical crystallization, self-assembly, and colloidal crystals are then discussed. This is followed by an exploration of mesocrystal systems, their formation, analysis, and properties. A unifying crystallization scenario combining classical and nonclassical crystallization is then presented, and the analogy between hierarchically structured crystals and biopolymers is made. Finally there is an overview of what might be possible in the future with an "extended crystallization toolbox". This book is essential reading for scientists involved in crystallization, materials science, self-assembly, colloid science, nanosciences, biomineralization, and graduate students of material science. it is also invaluable for dealing with highly complex crystal systems.