Sugar is not an essential ingredient for pizza dough. However, if used, it can serve multiple purposes. The main use of sugar is for color of the crust: the more you use, the darker the crust will be. Sugar also provides nutrients for the yeast to feed on.
If your flour is unmalted, you can use sugar to give the crust more color.
Sugar in a dough, if used in sufficient quantity (more than 3%), will also contribute to the sweetness of the pizza crust. In addition to its many functions of contributing to flavor, feeding the yeast and color of the crust, sugar also helps to make the crust and crumb more tender. The reason for this is that sugar is hygroscopic. In other words, it attracts moisture from the environment. As a result, it retains water in the dough, which translates into a more tender crust and crumb.
Simply mix the sugar into the flour along with the dry ingredients. When you’re using active dry yeast (ADY), you can add a pinch of sugar to the rehydration water to stimulate the yeast activation. Add the remaining sugar to the flour.