RESTING THE DOUGH: What does "letting the dough rest" mean?

This is a commonly recommended step in making bread or other leavened dough. It means that, after kneading or shaping the dough—depending on the recipe—you should leave it untouched for a specific period. This allows the dough to stabilize, particularly helping the gluten structure ("gluten network") to properly form.  

It is therefore always advisable to follow the recipe instructions and let the dough rest between the end of kneading and the next shaping phase. Place the dough in a lightly floured bowl or container, and cover it with a plastic sheet or a cloth to prevent it from drying out.