Stellar spectroscopy is the fundamental tool for investigating the natures of stars and is central to our understanding of modern astronomy and astrophysics. Revised and expanded, the second edition of this popular book provides a unique and thorough introduction to stellar spectra. It begins by introducing the reader to the fundamental properties of stars and the formation of spectra, before proceeding to the concept and history of stellar classification. The following chapters each look at a different star type: starting with cool M, the discussion extends to cover new stellar classes L and T, before advancing through type O to finish with extraordinary classes. The book concludes with a skilful integration of all the data, tracing the evolution of stars and their place in the Universe. With modern digital spectra and updates from two decades of astronomical discoveries, this accessible text is invaluable for both amateur astronomers and students.