Textbook in PDF format Researchers and students have not yet had access to a book which would enable them to trace the origins of the concepts that explain the behavior of materials under irradiation. This book fills the gap. As far back as antiquity, the notions of purity and disorder have been evoked to explain the different properties of materials. It was geologists who developed the subject in the 19th century. Then, with the discovery of X-rays and radioactivity, disorder in materials became the domain of physicists and chemists. The first observations focused on the color changes of ionic crystals, then gradually all the techniques for characterising materials were used. However, questions about the resistance of the components of the first atomic piles to irradiation led to the development of irradiation studies