Why does yeast dough need to rise?

Letting dough made with yeast “rise”, or rest, gives the yeast time to do its job. Yeast is a living organism which releases carbon dioxide gas as it feeds on the sugars in flour, a process called fermentation. That gas gets trapped in the gluten formed in the dough, causing the dough to expand.

The first rise after kneading (known as bulk fermentation) provides a lot of volume to the dough with large gas bubbles. The second rise after punching down and shaping (known as proofing) redistributes the yeast within the dough to give it more food, causing it to increase in volume even more, but with smaller bubbles that give the the baked bread or rolls a finer texture.

You can test if your dough has risen enough by gently pressing the dough with your finger. If the indentation remains, your dough is ready. If it quickly bounces back, give it more time.