Nanocomposites are engineered materials that incorporate nanosized particles into a matrix of a conventional material. These nanosized particles, called nanomaterials, when added into a matrix, are referred to as nano additives or nanofillers. Adding nanofillers can drastically alter the properties of a material, including its mechanical strength, toughness, thermal or electrical conductivity, and electromagnetic behaviour.

A composite is a multiphase material made up of two or more constituent materials with significantly different physical and chemical properties that do not blend or dissolve in each other. When combined, these constituent materials work in synergy to give a unique set of properties such as high strength-to-weight ratio, corrosion resistance and tailored electrical and thermal properties, which differ from the properties of the individual constituents. One constituent is called the reinforcing phase (or reinforcement), and the one in which it is embedded is called the matrix.