Ferroic materials are important, not only because of the improved understanding of condensed matter, but also because of their present and potential device applications. This book presents a unified description of ferroic materials at an introductory level, with the unifying factor being the occurrence of nondisruptive phase transitions in crystals that alter point-group symmetry. The book also aims to further systemitize the subject of ferroic materials, employing some formal, carefully worded, definitions and classification schemes. The basic physical principles leading to the wide-ranging applications of ferroic materials are also explained, while placing extra emphasis on the utilitarian role of symmetry in materials science.