"Modern Crystallography IV" is devoted to a systematic and up- to-date description of fundamental physical properties of solid and liquid crystals. These include elastic and mechanical, dielectric and ferroelectric, magnetic and optical properties, transport phenomena and spectroscopy. An important feature of the treatment is its use of the crystallographic approach, an introduction to which is given in the opening chapter of the book. The topics are treated at a level understandable to students who have two years of university physics. Researchers and engineers working on practical applications should also find the book useful, as should specialists in other fields who wish to broaden their knowledge of crystallography and materials science. The book is written by a group of leading scientists from the Institute of Crystallography of the USSR Academy of Sciences.