Electron tunnelling spectroscopy is a research tool which has strongly advanced understanding of superconductivity. With the invention of the scanning tunneling microscope, STM, by Nobelists G. Binnig and H. Rohrer, beautiful images of atoms, rings of atoms and of exotic states in high temperature superconductors have appeared. Some of the most famous images of any kind, at this date, are STM topographs. This book explains the physics and the instrumentation behind the advances illustrated in the famous images, and summarizes the state of knowledge that has resulted. It presents the current...