A composite is the combination of at least two materials with different physical or chemical properties combined to obtain properties that cannot be achieved by any of the components alone.
Typically, composites are made up of two components, the reinforcing phase and the matrix phase. The reinforcing phase is in the form of fibers, sheets, or particles and is embedded into the other materials, the matrix phase. The reinforcing material is usually strong with low density, while the matrix material is usually ductile or tough. Combined you get the strength of the reinforcing material and the toughness of the matrix material.