Nematic and Cholesteric Liquid Crystals is a result of personal research and of the graduate lectures given by the authors at the Ecole Normale Supérieure de Lyon and the Paris VII University, respectively. The first part of the book presents historical background, the modern classification of liquid crystals, and mesogenic anatomy; the second part examines liquid crystals with nematic and cholesteric orientational order. Several chapters analyze defects, surface anchoring transitions, and growth phenomena. The book provides a useful reference intended for advanced undergraduate and graduate students and researchers in liquid crystals, condensed matter physics, and materials science.