The book outlines the physical foundations of theoretical and observational cosmology. Particular attention is paid to the process of formation of the Hubble flow of matter in the general theory of relativity and the quantum-gravitational generation of density perturbations responsible for the emergence of galaxies and the structure of the Universe. In terms of the breadth of topics and depth of presentation, the book has no analogues. The book is intended for senior students in the physics departments of universities, graduate students and young scientists.