This handbook examines cutting-edge developments in research and applications of small or mesoscopic superconductors, offering a glimpse of what might emerge as a giga world of nano superconductors. Contributors, who are eminent frontrunners in the field, share their insights on the current status and great promise of small superconductors in the theoretical, experimental, and technological spheres. They discuss the novel and intriguing features and theoretical underpinnings of the phenomenon of mesoscopic superconductivity, the latest fabrication methods and characterization tools, and the opportunities and challenges associated with technological advances. The book is organized into three parts. Part I deals with developments in basic research of small superconductors, including local-scale spectroscopic studies of vortex organization in such materials, Andreev reflection and related studies in low-dimensional superconducting systems, and research on surface and interface superconductivity. Part II covers the materials aspects of small superconductors, including mesoscopic effects in superconductor–ferromagnet hybrids, micromagnetic measurements on electrochemically grown mesoscopic superconductors, and magnetic flux avalanches in superconducting films with mesoscopic artificial patterns. Part III reviews the current progress in the device technology of small superconductors, focusing on superconducting spintronics and devices, barriers in Josephson junctions, hybrid superconducting devices based on quantum wires, superconducting nanodevices, superconducting quantum bits of information, and the use of nanoSQUIDs in the investigation of small magnetic systems.