Candied ginger

Preserved ginger is made from young, fleshy rhizomes boiled with sugar and either packed in syrup or crystallized. That short description from A Dictionary of Food and Nutrition covers both forms of what bakers call candied or crystallized ginger.

Boiling the root in sugar both sweetens it and preserves it. The same principle is used for other candied fruit, which is preserved by soaking in syrup whose concentration is raised gradually until it is strong enough to prevent decay. The result keeps ginger's warm, spicy character but softened by sugar, and the crystallized form is coated with sugar so that it stays dry to the touch.

In baking, small pieces are used to add a bright, spicy sweetness to gingerbread, cookies and cakes, and to finish desserts.