This is the first non-technical book on this subject, written specifically for practical amateur astronomers. It includes all the science necessary for a qualitative understanding of stellar spectra, but avoids a mathematical treatment which would alienate many of its intended readers. Any amateur astronomer who carries out (or who is interested in) observational spectroscopy and who wants a non-technical account of the physical processes which determine the intensity and profile morphology of lines in stellar spectra will find this is the only book written specially for him. And of course, "armchair astronomers" who simply want to understand the physical processes which shape lines in stellar spectra will find this book equally fascinating.