"For centuries astronomers and cosmologists have attempted to answer some of the most fundamental questions about the nature of our Universe. This introductory textbook presents our current understanding of the role of galaxies as 'building blocks' in the Universe and explains why the distances between galaxies are increasing as time progresses." "Starting with a detailed discussion of the structure and history of our own Galaxy, the Milky Way, this textbook goes on to give a general introduction to normal and active galaxies with a description of their physical properties and their distribution in space. It includes a review of the methods astronomers are currently using to tackle questions about the formation and evolution of galaxies. The second part of the book provides an introduction to a wide range of cosmological models and emphasizes the interplay between theory and observation in determining the nature of the cosmos. Models of the big bang and the expansion of the Universe are discussed and the book concludes by highlighting outstanding problems in modern cosmology." Compiled by a team of experts, this textbook has been designed for elementary university courses in astronomy and cosmology, and is written in an accessible style that avoids complex mathematics. It is therefore suitable for self-study and will appeal to amateur astronomers as well as undergraduate students.