This book covers the important contributions of the Chinese during the development of high-temperature superconductors (HTS). The study of Y-based HTS, which was the first to be reported internationally at a liquid nitrogen temperature above 90 K, has retained the world record for superconducting transition temperatures. The book covers the study of superconducting energy gap, microscopic electron non-uniformity, ARPES research, "kinks" research, eHigh-T¿. In order to provide a comprehensive introduction to the physical properties of condensed matter, this book also includes studies on the thermodynamic properties of high-temperature superconductors, low-temperature heat transport, and Raman spectroscopy. In addition, this book includes important topics in theoretical studies, including the study of the magnetic and superconductivity of iron-based materials, the non-diagonal long procedure in condensed quantum phases, and the creation of oxygen sites in the CuO¿ plane. Rotational fluctuations lead to the study of superconducting states. This book is suitable for researchers and graduate students in condensed matter physics, materials science, optics and other fields.