Coppicing. What is it for? It's purpose & how to di it?

First, what exactly is coppicing? What purpose does it serve? I am an historian and, in my reading, I'll come across references to it - to whole coppiced woods. The impression I get is that it was a way of cutting trees (usually a large number of trees) to make the trees grow in a specific and useful-to-man way.

I've looked at the definitions available and they seem to be contradictory.

I've a practical interest in the answer as I am growing 4 Blackthorns in order to make walking sticks (I'm and old man!) and at least one shilleleagh to put above my non-existent mantle so as to tell people, 'I made that,' and bask in approving noises. Blackthorn should be coppiced, but that's thrown out there Like I should know how to coppice!

Thanks for your help.