This is a new and greatly revised edition of Professor Chandrasekhar’s classic book Liquid Crystals, first published in 1977. The subject of liquid crystals has grown into an exciting interdisciplinary research field with important practical applications. This book presents a systematic and self-contained treatment of the physics of the different types of thermotropic liquid crystals - the three classical types, nematic, cholesteric and smectic, and the newly discovered discotic type. Included is a description of the structures of these four main types and their polymorphic modifications, their thermodynamical, optical and mechanical properties and their behaviour under external fields. The basic principles underlying the major applications of liquid crystals in display technology and in thermography are also discussed. This book will be of great value to advanced students and researchers in condensed matter physics, chemical physics, materials science and technology with an interest in the physics, chemistry and applications of liquid crystals.