Hi P Cusco,
Some yeast is still needed in most recipes. It may be quite a small amount of instant or active dry yeast in a fairly wet dough, with 12 hours or more of fermentation, or the yeast may be in the form of sourdough that’s used, fed, and kept.
The yeast in the dough “exhales” carbon dioxide throughout the mass of dough. The network of gluten fibers, developed and strengthened by kneading (or perhaps long fermentation and folding) hold all those little exhalations and so the mass rises.
Happy exploring,
LS
