Home cooks use it principally to make icing or frosting and other cake decorations.
Powdered sugar is available in varying degrees of fineness, most commonly XXX, XXXX, and 10X: the greater the number of Xs, the finer the particles.
Canadian regulations limit powdered sugar to 5% starch or an anticaking agent.
It is commonly used in baking and cold mixed drinks because it dissolves faster than granulated white sugar.
It usually contains glucose, starch, and anti-binding agents (such as titanium dioxide, which gives it a vibrant white color), and retains its structure and look even when dusted onto baked goods that are slightly wet, such as fruit bars and tarts.