Why are there two layers in front of underwear?

In order to look good or cut, the surface materials of most underwear are not synthetic materials, so the materials will affect the normal physiological health of the human body, and it is these materials that can achieve the effects and requirements of the external structure. As a result, a second layer of material, usually cotton, is produced, which can be worn comfortably and has good air permeability.

Another reason is that the single-layer structure of some underwear will affect the appearance and be easily exposed, so the second layer material with better material is used to cover up some.