2.2 Rationale

Why do we use top-down design? The answer is quite simple: we cannot manage too many things at the same time.

Imagine you are managing photographs. Due to the ``no-cost'' nature of digital cameras, many people shoot thousands of pictures per year. If all pictures are thrown into the same folder for a few years, the folder will end up with so many pictures that it is impossible to find a particular one.

That's why we all have different ways to organize digital pictures.