The book "Cholesteric Liquid Crystals" offers a comprehensive analysis of the scientific concepts currently known about cholesteric liquid crystals. It discusses the molecular structure of the substances that form these crystals, as well as the various textures and unique physical properties they possess. Special attention is given to the applications of these crystals, particularly in medical diagnostics and art. The book describes the development of innovative devices based on the temperature-dependent color changes of cholesteric liquid crystals, including a diagnostic device for breast cancer that enables high-quality imaging, as well as a music color device that creates visual representations based on music frequencies. These applications demonstrate the potential of cholesteric liquid crystals in various fields of science and technology.