Diffuse X-ray scattering is a rich source of local structural information over and above that obtained by conventional crystal structure determination. The main aim of the book is to show how computer simulation of a model crystal provides a general method by which diffuse scattering of all kinds and from all types of materials can be interpreted and analysed. Since the first edition was published in 2004 there have been major improvements both in the experimental methods for recording diffuse scattering and in our ability to analyse it. The advent of new and better detectors means that fully 3-dimensional diffuse scattering data can be collected routinely for even quite small samples and computational power that is now available has continued its upward trend, meaning modelling calculations inconceivable in 2004 are now routine. The final part of the book traces these recent developments and outlines their future potential in the field.