Although the aim of the present work is to present the subject of surfactants from a practical point of view and with an emphasis on food chemistry, it is necessary for the theoretical basis of the subject to be presented in parallel. This has already been done in the previous chapter for thermodynamics, the physical chemistry of solutions, and the science of surfaces and interfaces, while the subject of the self-assembly of materials is covered in this chapter. It is the personal opinion of the author of the present work that a book concerning the science and technology of surfactants and colloids must not be limited to classical interface chemistry. New knowledge about the nature and organization of material reveals that the seemingly continuous phases are a macrocosm of interfaces and individual microphases and nanophases, a realization with huge practical consequences: The chemistry of biological systems has as its basis the chemistry of interfaces. Over the past three decades, additional steps forward in research into the organization of surfactants have shown that the seemingly anti-entropic processes of self-assembly are among the most important properties of nature and are probably the key to understanding not only the action of an emulsifier or a dye, but also the formation of life itself, the functioning of individual biochemical processes, and other broader philosophical questions.