Structures are the most powerful and flexible data type within ColdFusion, so powerful in fact that many internal variables are actually structures.
Simply put, structures provide a way to store data within data. Unlike arrays, structures have no special dimensions and are not like grids. Rather, they can be thought of as top-level folders that can store data, or other folders, which in turn can store data, or other folders, and so on. Structures can contain lists, arrays, and even other structures.