Once upon a time, airplane structures like the fuselage and wings were largely made of wood and fabric. Then much later on, aluminum being the latest of all metals was introduced in the mid 1920's and extensively used for aircraft manufacture up to this day.
By the mid 70's, glass reinforced plastic (GRP) was introduced for the production of minor airplane components such as doors, engine nacelles, etc. It is commonly called fiberglass and is said to be lighter and stronger than aluminum. This GRP material proved its worth and was further developed and strengthened by aviation structural engineers to be used in building even an entire airliners fuselage, its wings and control surfaces.
Today, our modern day Jumbos such as the Boeing 777 and Airbus are largely built of such composite material. Amazing, isn't it? It must be the age of plastics. Even cars, motorbikes, or high speed trains are now all made of composite material. I wonder what comes next after plastics. Paper planes perhaps?