This textbook provides a comprehensive and lucid modern introduction to galaxies for advanced undergraduate students in astronomy and physics. Basic astrophysics, multiwavelength observations and theoretical concepts are carefully combined to develop a thorough and integrated understanding. All the necessary background astronomy is included and mathematics has been kept to the minimum required to enable the student to grasp the essence of a calculation, or the basis for a method. Techniques for observation and measurement are clearly explained, with a critical review of their limits and accuracy. Exciting topics such as gravitational lensing, dark matter and galactic collisions and mergers are also covered. The clear and friendly style of the text, thorough coverage of fundamentals, extensive use of up-to-date observations, and helpful problems make this an ideal introduction to galaxies and an excellent preparation for more advanced texts and the research literature.