I remember the first time I learned about bannetons. I was trying to re-create a pain au levain that the U.S. bread team had developed and the instructions called for the dough to be proofed in a banneton. It was a lot of fun in those days, when I knew next to nothing about baking, to be constantly learning something new.
A banneton is a wicker basket that it used to proof bread. It can either be a half sphere or an oval in shape, and most often they are lined with linen so that the dough doesn't stick to the basket (though most of the time the banneton gets liberally floured either way). There are also bannetons made of plastic, which don't need to be lined and which hold the flour better than the traditional wicker.
You use the banneton in the final proofing stage, after it's been shaped and before you bake the bread. Flour the banneton, if needed, and place the dough in upside down so that the top is inside the basket and the bottom seam is visible.
Is a banneton completely necessary? Not really, but it can be a nice tool to have. You can find them for less than twenty bucks, or you can even make one yourself.The banneton shown in the picture is actually a homemade one from the Fresh Loaf. Sadly, I rarely use a banneton due to the production nature of most of my baking, but having one (or making one) for the occasional artisan loaf can be a great tool in your home baking arsenal.
I am the biggest 
Easter is a candy lover's dream, and 
What Can I Get You Folks? - Server Revenge
Reality-Show Celebrities Serve Up Chef Curtis Stone's 'Hundred-Dollar Burger'
Foods Celebrity Chefs Hate
