In-situ high-resolution electron microscopy is a modern and powerful technique in materials research, physics, and chemistry. In-situ techniques are hardly treated in textbooks of electron microscopy. Thus, there is a need to collect the present knowledge about the techniques and achievements of in-situ electron microscopy in one book. Since high-resolution electron microscopes are available in most modern laboratories of materials science, more and more scientists or students are starting to work on this subject.In this comprehensive volume, the most important techniques and achievements of in-situ high-resolution electron microscopy will be reviewed by renowned experts. Applications in several fields of materials science will also be demonstrated.