The German architect Axel Ritter has been collecting examples of innovative materials for more than a decade, and his book, Smart Materials in Architecture, Interior Architecture, and Design—published by Birkhäuser last December—is a colorful, example-packed, occasionally disorienting catalog of that effort. So what makes a material smart? For Ritter the key considerations are whether it has changeable properties, and whether the changes are repeatable and reversible. It can be as simple as a latex paint that shifts color based on room temperature, or as complex as Ritter’s own proposal for a “polyreactive mechanomembrane” that would alter the shape of a building’s skin based on weather conditions. “Materials are becoming more and more important because architects are now thinking about buildings that are dynamic and can adapt to their surroundings,” Ritter says. But they’re just as important for interior and industrial designers looking for new finishes, adaptive forms, and unusual effects. Here we present a few examples culled from Ritter’s book.