Nanomaterials show enhancement in the fundamental characteristics of bulk materials when their size is confined. This enhancement in the characteristics of nanomaterials lead them to have multiple applications in almost every sector. Also, the idea of nanomaterials is not a new concept as it existed way back for more than 4000 years. The overview, historical background, types of synthesis routes, its characterization and its applications in various sector have been discussed in the current chapter. Also, the change in properties of nanomaterials due to the confinement and surface area to volume ratio and the classification of nanomaterials has been elaborated. Hence the chapter explores the overview and historical background of nanomaterials in detail.