powdered sugar; icing sugar; 10X
Confectioners' sugar is pulverized granulated sugar that's been milled with a bit of cornstarch (about 3% to 4%). Since confectioners' sugar is so fine, it dissolves readily in any liquid or fat, hot or cold, so it's often used to sweeten uncooked foods without making them grainy. Its powdered texture also works beautifully to dust on desserts.
You can substitute 1/2 cup plus 1 Tbs. granulated sugar per 1 cup confectioner's sugar in a pinch, but the texture of the cake, cookie, or icing may suffer.
While shopping for sugar, keep in mind that the sugar industry has not standardized its labels, so stay alert to inconsistencies between brands.
Store in a sealed container in a cool, dry place away from strong odors, which its physical makeup makes it susceptible to picking up.