The formation of solids is governed by kinetic processes, which are closely related to the macroscopic behaviour of the resulting materials. With the main focus on ease of understanding, the author begins with the basic processes at the atomic level to illustrate their connections to material properties. Diffusion processes during crystal growth and phase transformations are examined in detail. Since the underlying mathematics are very complex, approximation methods typically used in practice are the prime choice of approach. Apart from metals and alloys, the book places special emphasis on the growth of thin films and bulk crystals, which are the two main pillars of modern device and semiconductor technology. All the presented phenomena are tied back to the basic thermodynamic properties of the materials and to the underlying physical processes for clarity.