Composite is consist of two phase, one is Reinforcing phase and other is Matrix. Reinforcing phase is like fibers, particles, flakes. Matrix  is a continuous phase. Example of composite: Concrete reinforced with steel, epoxy reinforced with fibers.      Naturally found : Bone-salt plates made of calcium and phosphate ions reinforcement soft collagen.  Some advanced composites are: graphite/epoxy, Kevlar/epoxy, fiber glass etc.