From DT Online

A Composite is a material created by bonding together two or more different materials to take advantage of the particular properties or characteristics of the contributing elements.

Commonly used Composites in everyday use include:

Plywood Plywood, together with other Manufactured Boards, exploits the strength of wood along its Grain by gluing together thin layers (i.e. Veneers) at an angle to each other to create a material which has strength in all directions. In addition, the appearance of Manufactured Board composite materials can be enhanced by adding a further Lamination of plastics or a more exotic hardwood Veneer for example.
Birch plywood
Glass reinforced Plastics (GRP) Commonly known as 'fibreglass', GRP is made by reinforcing a resin matrix with fibres. Typically, polyester or epoxy resin is reinforced with glass strands or carbon fibre but other combinations are possible.
Glass reinforcements
Concrete Concrete has been used since the time of Ancient Rome and, at its simplest, comprises a stone aggregate suspended within a Portland Cement matrix. Concrete can be strengthened further by adding steel reinforcement known as Rebar and Weldmesh - or even Textiles. Prestressed Concrete uses pre-tensioned steel rods or wires to improve load bearing.
Concrete rebar 0030
Overhead power lines These are seen suspended between pylons transmitting electricity across the country. Aluminium is used as the main conductor and wrapped around a core material chosen to provide greater tensile strength to avoid excessive sag between pylons. Most commonly a steel core is used but more modern cables may have carbon and glass fibre reinforcement.
ACSR & ACCC Conductors
Sheffield Plate consists off a thin layer of silver fused on to one or both sides of a copper or nickel silver core. It was discovered accidentally in the mid-eighteenth century and used for about 100 years until superseded by electro-plating which was developed in the mid-nineteenth century.
Tankard MET 182180