In 1959, about 1400 compounds forming liquid crystalline phases were known; by 1992, this number had increased to about 50 000. In portable devices like wristwatches, pocket caculators, measuring instruments, and laptop computers the liquid crystal display technology has gained total acceptance and is on the way to encompass the market of colour TV screens. This development makes a volume devoted to liquid crystals in the series Topics in Physical Chemistry desirable. Following the concept of this series, an easy introduction to liquid crystals is given, enabling the reader to understand the basic problems of liquid crystals research and application. Because of the widespread field of different research activities in liquid crystals and applications, various competent authors have been involved in writing chapters on: - Phase types, structures, and chemistry of liquid crystals; - Thermodynamical behavior and physical properties of thermotropic liquid crystals; - Liquid crystalline polymers; - Lyotropic liquid crystals; - Application of liquid crystals in spectroscopy; - Application of liquid crystals in display technology.