This chapter presents a systematic categorization of the functionalities of silica shells in the context of their application fields. It provides a brief overview of the established synthesis strategies for noble metal/silica hybrid particles, including both dense and mesoporous shells. The chapter highlights some recently developed, less common preparation methods as well as examples of more complex nanostructures such as Janus particles and their assemblies. It discusses what we consider the most important practical applications of plasmonic nanocomposites, explaining the rationale behind typically employed designs and suggesting possible directions for further research. The chapter also provides an overview of various objectives that can be fulfilled by silica shells. These can be categorized into four main motivations for encapsulating metal nanoparticles with silica (or other metal oxides), namely, stabilization of the cores, insulation from the surrounding medium, templating of novel structures, and controlling molecular transport through the pores.