I've looked up all I can about what the skin is, and so far I understand it to be the top/bottom. I can only think of one reason as to why it is called the skin and not the more straightforward top/bottom, and that is that skin is only 4 letters.
Am I right? Is there more to it than just making it shorter?
edit: I just barely saw a setting in cura called "skin edge support thickness". I'm confused. Why do you need to support just the edge of the top? Can someone like take an image of a 3d print and color in the skin is?