Nobel laureate Steven Weinberg's monumental monograph summarizes the progress made in modern cosmology over the past two decades. It is unique in the scope of the material, the manner of its presentation and the thoroughness of its mathematical elaboration. The purpose of the book is to provide a closed description of cosmology, as well as the ideas and formulas that are used and tested in modern cosmological observations. For the first time, such comprehensive material on the current state of the theory has been collected in one book. “Cosmology” can be organically divided into two parts. The first four chapters are devoted mainly to consideration of an average isotropic and homogeneous Universe. They analyze such fundamental blocks as the evolution of the Universe until the formation of galaxies, cosmic microwave background radiation, the early Universe, the inflationary period, etc. The second part of the book (chapters 5-10) is devoted to the analysis of various deviations of the Universe from the average state. Here the general formalism and its application to the evolution of inhomogeneities are presented, the anisotropy of the cosmic microwave background radiation, large-scale structure, gravitational lensing, etc. are analyzed. The book does not simply report the results obtained by numerical calculations, but emphasizes the analytical description of cosmological phenomena, allowing one to penetrate into their essence. “Cosmology” describes in detail many of the most daring modern ideas that are rarely found in reviews of cosmology and for the study of which you need to dive into special articles. The monograph also presents current measurements of cosmological parameters in order to give the reader an idea of the successes of observational science. The appendices collect technical material necessary for understanding the main text of the book, present a glossary of notations, and give a selection of interesting problems. The monograph contains an excellent, comprehensive list of references with links to original articles.