The young science of electrolytic deposition of metals is a prime example of a frontier field. Here, electrochemistry, metallurgy, crystal physics, and surface chemistry intersect at every turn, and often chemical kinetics, thermodynamics, colloid chemistry, hydrodynamics, and more join in as well. Given such a variety of subjects, it is indeed a risk to attempt to write a book on the topic. It is no surprise, then, that a fundamental work on the scientific aspects of this field has been lacking until now. The fact that the author had the courage to undertake such an endeavor is likely no coincidence: as an electrochemist by inclination and as a supervisor of materials research in a large industrial company, he believed he was reasonably equipped for this challenging task. His own lectures served as a foundation. It was essential that such a work be written, and there was no time to waste. While technology has developed the field of electrolytic metal deposition to an admirable level over many years, it has undoubtedly retained initiative and leadership from the very beginning. However, a development that only follows a technical path eventually reaches a limit. For years, progress has become scarcer, yielding nothing fundamentally new. Today, this technology urgently requires inspiration that research can provide. Yet, our field still lacks the necessary scientific foundation. Establishing such a foundation is the main goal of this work.