This is a new and greatly revised edition of Professor Chandrasckhar's classic book Liquid crystals, first published in 1977. In this second edition the author has brought the subject completely up to date.The subject of liquid crystals has now grown to become an exciting interdisciplinary field of research with important practical applications. This book presents a systematic and self-contained treatment of the physics of the different types of (hcrmolropic liquid crystals the three classical types, nemalic, cholesteric and smeclic, composed of rod-shaped molecules, and the newly discovered discotic type composed of disc-shaped molecules. The coverage includes a description of the structures of these four main types and their polymorphic modifications, their thermo-dynamical. optical and mechanical properties and their behaviour under external fields. The basic principles underlying the major applications of liquid crystals in display technology (for example, the twisted and supertwisted nemalic devices, the surface stabilized ferroelectric device. etc.) and in thermography are also discussed.