In the first edition of the book under the title High-Temperature Superconductivity: Experiment and Theory experimental data obtained till the middle of 1994 were presented. Since then the experimental results have been greatly improved and consolidated. A new chapter on the recent achievements in applications of high-temperature superconductors is included in the second edition in order to reflect recent progress in this field. The main goal of the book is to provide an up-to-date and comprehensive review of the physical properties of copper oxide superconductors. It includes a survey of experimental results concerning structural, magnetic, thermodynamic, electronic and lattice properties in normal and superconducting phases.