Introduction to cosmology
The book is slower paced than more advanced works, and doesn't go as deeply into astrophysics. Most of the book concerns what happened in the early universe at or before the time of recombination. The main focus is explaining how the current proportions of dark matter and dark energy in the universe have been arrived at. Hence there are chapters on the cosmological microwave background, nucleosynthesis and element ratios, inflationary cosmology and the formation of structure from early inhomogeneities. If you have heard about these things from popular science books and want to know more mathematical details about how they are used to find the fundamental parameters of the universe, then you should consider working through this book.