Glass fiber reinforced (GFRP) Composites is the largest segment in the composites industry, worth several billions. Glass fiber is made from extremely fine fibers of glass.
It is a lightweight, extremely strong, and robust material. Although strength properties are somewhat lower than carbon fiber and it is less stiff, the material is typically far less brittle, and the raw materials are much less expensive. Its bulk strength and weight properties are also very favorable when compared to metals, and it can be easily formed using molding processes. The glass fibers are most extensively used as a raw material for composite materials.
For more info: Glass Fiber & Glass Fiber Reinforced Plastic (GFRP) Composites Market