This chapter explains what nanomaterial-based products are and how these impact our life and the global ecosystem. It provides a selection guide for physicochemical–biological analysis by commenting critical parameters affecting measurements. The chapter describes regulations and agencies related to the European Union (EU) legislation on nanomaterials and products. Nanomatter is a very general term used to indicate “objects” sized in the nanometric scale without giving details on their characteristics and/or properties. However, in general speaking only the nouns “nano-materials” and “nanoparticles”, or “nanocomposite” and “nanodevice” are used for a general audience. The ability of a nanomaterial to release ions in biological media for simple contact or in a biological defensive environment, or maybe triggered by concurrent physical parameters should also be assessed. Several nanomaterial parameters, such as chemical composition, size, shape, density, and surface area and how they change in biological media are important when indicating administered dose.