This is the first book to weave together into a coherent picture various recent studies of the different phases of condensed matter. Of the many known phases of condensed matter, the crystalline state has received most attention, and although noncrystalline states, for example liquid crystals, have also been extensively studied, this has been mostly without reference to interrelations between phases. This book gives an integrated overview with emphasis on physical aspects. The treatment is substantially descriptive, so although the key ideas involved are rather sophisticated the book should be accessible not only to experimental physicists but also to chemists, materials scientists, metallurgists and ceramicists whose work touches on condensed matter physics. Particular stress is laid on the role played by symmetry and symmetry breaking, and on the uses of symmetry concepts in the systematic classification of defects. The ground is also prepared for the possible future development of a field theory capable of describing both structure and dynamics. A series of technical appendices prepare the more mathematical reader for a deeper pursuit of the subject.