A composite makes use of the properties of two or more materials. Concrete and plastic-reinforced glass are two examples of composites.

Concrete can stand large squashing forces but is easily broken by small bending forces. By contrast, steel rods cannot stand large, squashing forces but they can stand large bending forces. By placing steel rods into concrete the best properties of both materials are used. This is called reinforced concrete.

Glass is a hard, transparent material but it is brittle. Plastic is a soft transparent material that is not brittle. When a sheet of plastic is placed between two sheets of glass a composite is made which is transparent, has a hard surface and does not break into jagged pieces when it is struck by a large force. This material is known as plastic-reinforced glass and is used in glass doors and car windscreens.