This chapter provides a broad overview highlighting the overall structure and the key contents of this book. Several basic taxonomies of ions and plasmas are first introduced as refreshers. With this foundational knowledge follow discussions on the focus areas and the threads among the chapters. The main themes of discussions center around basic sciences and processes for generating a wide variety of ions and plasmas, methodologies for measurements of their characteristics, approaches for utilizations of unique characteristics of ions and plasmas, principles of interactions of ions and plasmas with materials (including soft matters), and roles of ions and plasmas in emerging interdisciplinary applications. With merits to equip the readers with the skills of data sciences and advanced computational methods, the highlights of two chapters on special topics, namely, machine learning methodologies and mathematical foundations for quantum computing in plasma physics, are briefly narrated. Finally, the basic philosophy of this book and its differentiated values are indicated. Of noteworthy are sufficient generalities in the discussions and illustrations, so readers perpetuate advancing their academic pursuits through the conduits of plasma sciences and engineering, especially through utilizations of unique merits of ions and plasmas and explorations of opportunities for a diverse range of emerging applications.