How well your dough holds its shape and resists spreading -- a combination of gluten development, surface tension, and proper fermentation.
Strong dough bounces back when poked, holds a smooth, taut surface, and doesn't stick excessively to your hands. You build dough strength through kneading, stretch and folds, and proper shaping technique. During fermentation, enzymes and bacteria gradually break down gluten, so your dough starts strong and becomes more extensible over time. The art is stopping fermentation while the dough still has enough strength to hold its shape.
