This textbook has been designed by a team of experts for introductory university courses in astronomy and astrophysics. Beginning with a description of the structure and history of the Milky Way, it introduces normal and active galaxies in general. A wide range of cosmological models are then presented, including a discussion of the Big Bang and Universe expansion. The text contains numerous useful learning features such as boxed summaries, student exercises with full solutions, and a glossary of terms. It is also supported by a website hosting further teaching materials. Written in an accessible style that avoids complex mathematics, the book is suitable for self-study.