The icing sugar is a sugar characterized for being milled to powder (crystals with a diameter less than 0.15mm) with an addition of 2 or 3% of starch. Is used in baking to cover and give a decorative finishing touch to desserts or sweets. Mixed with hot water and lemon, produces the glaze which is used to decorate desserts like strudel cake.
The name comes from the French glasé (pronounced glas), used in the culinary expression sucre glasé (Ice sugar) Hence comes the English name Ice Sugar
The reference to the ice is due to the appearance that allows to get in many pastry preparations. Mixing the sugar with a little bit of water, you can get a paste with which you can cover and decorate cakes and sweets, and, when dry, forms a thin layer of an elegant white and crispy brightness.