Glass fiber is a material consisting of numerous extremely fine fibers of glass.
Glass fiber has favorable mechanical properties similar to other fibers. Although not as rigid as carbon fiber, it is much cheaper and significantly less brittle when used in composites. Glass fibers are therefore used as a reinforcing agent for many polymer products; to form a very strong and relatively lightweight fiber-reinforced polymer (FRP) composite material sometimes called glass-reinforced plastic (GRP), also popularly known as "fiberglass". It is used structurally due to its strength and relatively low weight.
Glass fiber is formed when thin strands of silica-based or other glass like formulations are extruded into many fibers with small diameters.
The most common types of glass fiber used are E-glass , C-glass and S-glass.