Refer to figures.
The figure shows the main structural components of a typical light aircraft wing. Let's look at some of the components in more detail to see what they do:

• Spars: Are the main beams which extend along the wingspan. These parts carry the stresses due to the vertical bending moments (These are the main loads in flight).
• Ribs: Ribs are fitted around the spars, giving shape to the wing.
• Stringers: Help to transfer loads from the skin to the main spar(s)
• Skin: The skin is the aerodynamic surface of the wing. It's main purpose is aerodynamic, although in some wing types it can also carry some of the in-flight stresses.

The Ribs are shaped in the 2D profile of the wing (its cross-section). As such, they determine the wing chord, camber, thickness and overall shape.

Longerons are part of the fuselage structure - they run longitudinally and carry the main fuselage structural loads. They are not part of the wing structure.