I'm not sure why, but whenever I tried to come up with a "U" word, all that I could think of was umbrella. I guess it goes back to school and learning the alphabet...A is for apple, B is for ball and so on. I can't remember all of them. Dog, elephant, goat, igloo, kangaroo, lion, monkey, queen, ring, top, yo-yo and zebra are the others I seem to remember.
I also thought of underwear. Though I have no clue why.
So, what do underwear and umbrellas have to do with writing? Well, I'm not sure but let's see if we can connect 'em. Underwear should be worn under and not seen. Umbrellas have that wire (usually) frame that no one pays attention to unless it doesn't work.
Stories also have a frame that we don't usually see. The "underwear" of a story is something no one pays attention to. And just like panty lines, no one wants to see how stories are put together. Now, as writers, we do notice how a great story is put together, how it just seems to flow without any effort. We know a lot of work went into getting it just right though.
And in honor of story structure here's a great place to check out. StoryFix