Salt also makes the dough a little stronger and tighter.
Salt impacts the shelf life of baked goods, but its effects depend on weather conditions. Salt is hydroscopic, which means it absorbs water. Consequently, in humid climates, it will trap moisture from the air, making a crisp crust soggy, and therefore shortening shelf life. In dry climates, however, the salt helps hold water in the bread longer, inhibiting staling, and thus extending the bread's shelf life. Salt, of course, adds flavor to baked goods.