 The addition of inorganic spherical nanoparticles to polymers allows the modification of the polymer's physical properties as well as the implementation of new features in a polymer matrix. This review article covers considerations on special features of inorganic nanoparticles, the most important synthesis methods for ceramic nanoparticles and nanocomposites, nanoparticle surface modification, and composite formation, including drawbacks. Classical nanocomposite properties, as thermomechanical, dielectric, conductive, magnetic, as well as optical properties, will be summarized. Finally, typical existing and potential applications will be shown with the focus on new and innovative applications, like in energy storage systems. This article was authored by Thomas Hanaman and Dorothy Vingdasabo.