Almost 50 years have passed since the famous papers of Hugo Rietveld from the late sixties where he describes a method for the refinement of crystal structures from neutron powder diffraction data. Soon after, the potential of the method for laboratory X-ray powder diffraction was discovered. Although the method is now widely accepted, there are still many pitfalls in the theoretical understanding and in practical daily use. This book closes the gap with a theoretical introduction for each chapter followed by a practical approach. The flexible macro type language of the Topas Rietveld software can be considered as the defacto standard.