With the pace of time, synthesis of nanomaterials has paved paths to blend two or more materials having different properties into hybrid nanoparticles. Therefore, it has become possible to combine two different functionalities in a single nanoparticle and their properties can be enhanced or modified by coupling of two different components. Core-shell technology has now represented a new trend in analytical sciences. Core-shell nanostructures are in demand due to their specific design and geometry. They have internal core of one component (metal or biomolecules) surrounded by a shell of another component. Core-shell nanoparticles have great importance due to their high thermal stability, high solubility and lower toxicity. In this review, recent progress in development of new and sophisticated core-shell nanostructures has been explored. The first section covers introduction throwing light on basics of core-shell nanoparticles. Following section classifies core-shell nanostructures into single core/shell, multicore/single shell, single core/multishell and multicore/multishell nanostructures. Next main section gives a brief description on types of core-shell nanomaterials followed by processes for the synthesis of core-shell nanostructures. Ultimately, the final section focuses on the application areas such as drug delivery, bioimaging, solar cell applications etc.