crochet newbie...

[deird1]

Yesterday I finished my very first scarf (yay!) and went off to the wool shop to buy more wool for my next project. And the woman selling me wool asked "You know you have to wind it into a ball first, right?"

To which I nodded and smiled, despite having no clue about this whole "wind it into a ball" thing.

So, fellow crocheters: what is the reason behind this mysterious command to wind balls of wool? What is it for?