Book excerpt: This third edition has been extended considerably to incorporate more information on instrument influences on the interpretation of X-ray scattering profiles and reciprocal space maps. Another significant inclusion is on the scattering from powder samples, covering a new theoretical approach that explains features that conventional theory cannot. The new edition includes some of the latest methodologies and theoretical treatments, including the latest thinking on dynamical theory and diffuse scattering. Recent advances in detectors also present new opportunities for rapid data collection and some very different approaches in data collection techniques; the possibilities associated with these advances will be included. This edition should be of interest to those who use X-ray scattering to understand more about their samples, so that they can make a better judgment of the parameter and confidence levels in their analyses, and how the combination of instrument, sample and detection should be considered as a whole to ensure this.