This book is written largely in terms of the relationship between cosmology and the physics of the microcosm. It presents results relating to a homogeneous isotropic universe at the hot stage of its evolution and at subsequent cosmological stages. The main sections discuss the established ideas about the early and modern Universe; these sections can serve as a modern introduction to this rapidly developing field of science. To facilitate the reading of the main sections in the annexes, the necessary information from the general theory of relativity and the theory of elementary particles is given. In addition, the book discusses hypotheses (often alternative to each other) relating to unsolved problems of cosmology, such as the problems of dark matter, dark energy, asymmetry between matter and antimatter, and so on. d. It is assumed that in the future a continuation will be written devoted to the theory of the development of cosmological perturbations, inflationary theory and the theory of post-inflationary heating. For researchers, graduate students and students specializing in particle physics and cosmology.