Sugars or sweetening agents have the following purposes in baking:
They add sweetness and flavor.
They create tenderness and fineness of texture, partly by weakening the gluten structure.
They give crust color.
They increase keeping qualities by retaining moisture.
They act as creaming agents with fats and as foaming agents with eggs.
They provide food for yeast.
We customarily use the term sugar for regular refined sugars derived from sugarcane or beets. The chemical name for these sugars is sucrose. However, other sugars of different chemical structure are also used in the bakeshop.