Noble metal nanoparticles have attracted enormous scientific and technological interest because of their unique optical properties, which are related to surface plasmon resonances. The interest in nanosized metal particles dates back to ancient societies, when metals were used in various forms as decorative elements. From the famous Lycurgus cup, made by the Romans in the 4th century AD, through thousands of stained glasses in churches and cathedrals all over medieval Europe, bright-yellow, green, or red colors have been obtained by a touch of metallic additions during glass blowing. This peculiar interaction of light with nanometals can be widely tuned through the morphology and assembly of nanoparticles, thereby expanding the range of potential applications, from energy and information storage to biomedicine, including novel diagnostic and therapeutic methods. This book compiles recent developments that clearly illustrate the state of the art in this cutting-edge research field. It comprises different review articles written by the teams of Prof. Luis Liz-Marzán, an international leader in chemical nanotechnology who has made seminal contributions to the use of colloid chemistry methods to understand and tailor the growth of metal particles at the nanoscale. Apart from synthesis, the book also describes in detail the plasmonic properties of nanomaterials and illustrates some representative applications. This book will appeal to anyone involved in nanotechnology, nanocrystal growth, nanoplasmonics, and surface-enhanced spectroscopies.