This book aims to describe in detail the electron microscopy methods used to investigate complex and fine-scale microstructures, such as those produced by fast-particle irradiation of metals or ion-implantation of semiconductors. Particular attention is given to the methods used to characterize small point-defect clusters such as dislocation loops, since the coverage of this topic in general microscopy textbooks is limited and omits many of the problems associated with the analysis of these defects. In-situ, high-resolution and analytical techniques are also described. The techniques are illustrated with examples, which serve to give an overview of the contribution of TEM to the present understanding of radiation damage mechanisms. The book will be most useful to researchers in, or entering into, the field of defect analysis in materials.