This valuable text begins with the general theory of diffraction through the use of Fourier transforms. The author then applies the general results to various atomic structures including amorphous bodies, crystals, and imperfect crystals, whereby the elementary laws of x-ray diffraction from ideal structures follow as a special case. The presentation has been carefully developed to illustrate clearly the meaning of the general equations essential for the study of more complex cases. Readers are assumed to be familiar with the elements of crystallography and x-ray diffraction, and the author has not discussed the problem of determining crystal structures. Rather the focus is on the great variety of imperfect crystals as well as amorphous bodies and liquids. The book should thus be especially useful for solid-state physicists, materials scientists, chemists, and biologists with an interest in the scattering from defective structures. More generally, it will benefit all who require a thorough understanding of diffraction theory in order to interpret properly the information provided by modern x-ray diffraction instruments on line profiles, line intensities, diffuse scattering, and other phenomena associated with disorder.