Metallic nanoparticles have a rich historical presence, having been utilized in ancient artifacts long before the advent of modern nanotechnology. Among these artifacts are the legendary Damascus sword, renowned for its strength and sharpness and the vibrant colors of stained-glass windows in medieval churches. It was not until the discovery of the scanning electron microscope that scientists began to understand the extraordinary properties of these ancient marvels. This book delves into the science behind why metallic nanostructures exhibit such exceptional behaviors, including their unique physical properties and the underlying principles that govern them. This book provides an in-depth look at the methods used to fabricate these structures, the techniques for characterizing and modeling them, and the wide range of applications they have in today's technology-driven world. From medical diagnostics and electromagnetic detection to energy storage, the potential of metallic nanostructures is vast and ever-expanding.