The electrochemical dissolution of clean, oxide-free metal surfaces in electrolyte solutions is a fundamental process in metal corrosion as well as in technological etching and metal-refinement processes. Due to fundamental interest and for industrial reasons, dissolution processes and the effect of organic corrosion inhibitors have been studied intensely, concentrating on the determination of macroscopic etch rates and the effect of varying chemical parameters upon the etch kinetics. In the 1920s, ideas for the microscopic mechanism of the dissolution and the reverse deposition reaction had already been put forward by Stranski, who suggested that dissolution (growth) is dominated by detachment (attachment) of atoms at low coordination sites of the crystal surface and at kink sites along monoatomically high steps (see the schematic model in Figure 1). These kink sites are preserved during the removal (or addition) of the basic building blocks of the crystal (e.g., single metal atoms for elemental metals) and hence can sustain a continuous dissolution reaction. However, the direct verification of these ideas was impossible for more than seven decades, due to the very complex (defect) structure of the surfaces of typical metal electrodes, the presumably dominating effects of these defects on the etch process, and the lack of structurally sensitive probes suitable for in situ structural characterization.