Despite the significant progress in the study of point defects in metals, some important problems still do not have unambiguous solutions. One the most practically important questions relates to equilibrium defect concentrations. There exist two opposite viewpoints: (1) defect contributions to physical properties of metals at high temperatures are small and cannot be separated from the effects of anharmonicity; the equilibrium defect concentrations at the melting points are in the range of 10-4 to 10-3; (2) in some cases, defect contributions to the specific heat of metals are much larger than nonlinear effects of anharmonicity and can be separated without crucial errors; the equilibrium concentrations at the melting points are of the order 10-3 in low-melting-point metals and 10-2 in high-melting-point metals. This work discusses the experimental results and theoretical considerations favouring each claim. At the time of publication, the majority of the scientific community hold the first viewpoint. Regrettably, the data supporting the second viewpoint has not been displayed and discussed together, and the criticism of this viewpoint has never included a detailed analysis. Important arguments supporting this viewpoint appeared in the 1990s. In this book, the main attention is paid to equilibrium point defects in metals and their relation to thermophysical properties of metals. Along with a discussion on experimental data and theoretical estimates now available, some approaches are proposed that seem to be most suitable for settling the question.