A composite material is a material made from two or more constituent materials with notably dissimilar chemical or physical properties that are merged to create a material with properties unlike the individual elements. Within the finished structure, the individual elements remain separate and distinct, distinguishing composites from mixtures and solid solutions. The two main components within a composite are the matrix and fiber. The matrix is the base material while the fiber is what reinforces the material. Composites can also include core materials, fillers, additives, and surface finishes to provide unique performance attributes.

Typical engineered composite materials include reinforced concrete and masonry, composite wood such as plywood, and reinforced plastics such as fiber-reinforced polymer or fiberglass. A sandwich-structured composite is a special class of composite material that is fabricated by attaching two thin but stiff skins to a lightweight but thick core. The core material is normally low strength material, but its higher thickness provides the sandwich composite with high bending stiffness with overall low density.

Composites are all around us, and they can be natural or synthetic. Wood, a natural composite, is a combination of cellulose or wood fibers and a substance called lignin. The fibers give wood its strength, while lignin is the matrix or natural glue that binds and stabilizes them. Other composites include concrete, mud bricks, and fiberglass.

In summary, composites are materials made from two or more different materials that, when combined, are stronger than those individual materials by themselves. They are typically designed with a particular use in mind, such as added strength, efficiency, or durability. Composites can be made from a variety of materials, including natural and synthetic fibers, and they are used in a wide range of applications, from construction to aerospace to sports equipment.