By integrating two or even more materials whose properties are quite distinctive is composite materials. The different materials work together to build special properties for the composite, but within the composite one can easily tell the various materials apart that they don't dissolve or mix together.
It is also recognized as Fiber-Reinforced Polymer (FRP) composites, which are constructed from a polymer matrix strengthened with engineered, man-made or natural fiber like glass, steel or aramid or other strengthening material.