FRP is a composite made up of thermosetting resins and fiberglass, which is very thin fibers of glass, hence the name. It is a composite material made of a polymer matrix (resin) with fiber,glass, carbon or basalt. The polymer matrix is developed via a step growth or additional polymerization.
The resins are what contribute the various environmental and chemical resistance qualities and act as the binder for the glass fibers within the structural layer.