This volume provides a comprehensive introduction to the theory of d-wave superconductivity, focused on d-wave pairing symmetry and its physical consequences in the superconducting state. It discusses the basic concepts and methodologies related to high-temperature superconductivity and compares experimental phenomena with theoretical predictions. After a brief introduction to the basic theory of superconductivity and several models for high-temperature superconductivity, this book presents detailed derivations and explanations for various single-particle and collective properties of d-wave superconductors that can be monitored experimentally, including thermodynamics, angular-resolved photo-emission, single-particle and Josephson tunnelling, impurity scattering, magnetic and superfluid responses, transport and optical properties and mixed states. Various universal behaviours of d-wave superconductors are highlighted. Aimed primarily at graduate students and research scientists in condensed matter and materials physics, this text enables readers to understand systematically the physical properties of high-temperature superconductors.