The study of "soft matter" materials with complex properties has raised a number of interesting problems in basic physics, biology, and materials science, all of which promise new and important technological applications. After a review of chemical bonds and phase transitions, the authors treat topics such as surface phenomena, stability of colloidal systems, structural properties of polymers, and topological defects. The monograph's emphasis on underlying physical principles offers a coherent treatment of the great variety of research in the field.