Metal nanoclusters, which bridge metal atoms and nanocrystals, are gaining attention due to their unique chemical and physical properties which differ greatly from their corresponding large nanoparticles and molecular compounds. Their electronic and optical properties are of particular interest for their use in sensing, optoelectronics, photovoltaics and catalysis. The book highlights recent progress and challenges in size-controlled synthesis, size-dependent properties, characterization and applications of metal nanoclusters. Specific topics include organochalcogenolate-stabilized metal nanoparticles, water-soluble fluorescent silver nanoclusters, thiolate-protected Au and Ag nanoclusters, DNA-templated metal nanoclusters, fluorescent platinum nanoclusters and janus nanoparticles by interfacial engineering. Edited by active researchers in the area, the book provides a valuable reference for researchers in the area of functional nanomaterials. It also provides a guide for graduate students, academic and industrial researchers interested in the fundamentals of the materials or their applications.