What is icing sugar and how is it used in baking and cooking?

Icing sugar, also known as powdered sugar or confectioner's sugar, is a finely ground sugar mixed with a small amount of cornstarch. It is commonly used in baking and cooking to make frosting, glazes, and decorative toppings for cakes, cookies, and pastries. It dissolves easily and creates a smooth texture, making it ideal for creating a sweet and smooth finish on baked goods.