This is a basic and critically important part of making any piece of pottery because not removing the air bubbles usually results in the destroying the pot because the air expands as the kiln heats up and then it explodes. Even the best of potters has it happen occasionally and it's always disappointing because it's a waste of both time and money. In the worst cases, the exploding pots destroy a few other pots in the same firing, which only makes the whole thing worse.
In fact, it just happened to me recently and I thought I'd share some two views of the same pot at the bisque stage so you can see the havoc that a few little air bubbles can create.
So the next time you are admiring a platter, pot or any piece of ceramic art, imagine its humble origins as a lump of wet clay giving the potter a good upper-body work out as they rolled and folded all the little air bubbles out of it.