Book excerpt: The use of smart materials in architecture is a dynamic and innovative area merging research, development, and use. Smart materials, with their reversible characteristics, respond to stimuli such as light, temperature, and electrical field by changing their form, color, viscosity, etc. One of the most fascinating developments is the advent of Phase Change Materials. These materials make it possible, for example, to develop self-acting, kinetic facades and wallpaper that changes its color and pattern based on temperature and light. The book presents the development of these materials and also describes their use in the contexts of architecture, design, and art. It offers a systematic overview with a detailed discussion of properties, technologies, products, and projects based on twenty groups of smart materials.