The A319/A320/A321 are narrow body, twin-engined, short / medium-range aircraft, the A319 being the shortened version of the A320, and the A321 being the stretched version of the A320.
Drawing of the wing of an Airbus 300
The main structure of fusleage typical sections is primary, made of aluminum-alloy. It has skin plates, frames, stringers and skin stiffeners, they are riveted together to make the fuselage shell. Top beams and seat tracks, riveted to crossbeams make the cabin floor stronger. Support struts and diagonal braces make the fuselage structure stronger.