How Big Is This Folder? Recursion

Work out how big a folder is when it holds folders, which hold more folders, as deep as anyone made them: why one loop, a loop in a loop and a loop per level all come up short, and the idea that fixes them, recursion.

Updated

Cheat sheet: How Big Is This Folder? Recursion
Category
Data Structures
Level
Apprentice
Tags
Base Case, data structures, Recursion (data-structures), Recursive Case