Gluten is that magic protein that gives pizza and other breads their wonderful stretch that leads to a great interior crumb and a crispy crust. I'll talk more later about gluten specifics but thought for now just a quick picture is worth a bunch of words. This is one of the dough "balls" that's been fermenting and enlarging on a baking sheet. Because it stuck against another dough ball, when I separated them it tore a bit. And what do we see? Inside that smooth exterior is a honeycomb of linked strands of dough going every which way. As the dough ferments, the yeast gives off carbon dioxide (yeast farts!) and the gas is trapped at bubbles. But rather than expanding outward like a balloon (which can also happen) the more regular thing is to expand a bit here and a bit there and a bit everywhere. The structural "girders" of the dough ball - the gluten proteins - hold it all together, leading to a puffy dough that just loves to either rise in the oven after its been shaped into a loaf or into a pizza disk. Pretty neat looking, yes?