Brown sugar is a type of sugar that contains molasses, which gives it its distinct color, flavor, and moisture. Brown sugar can be made by adding molasses syrup to boiling sugar crystals that result from the sugar-refining process, or by coating white granulated sugar with molasses. While sugar beets and sugar cane are used to make white granulated sugar, only molasses from sugar cane is used in the production of brown sugar. The amount of molasses added to the sugar determines whether it is light or dark brown sugar. Light brown sugar contains about 3.5% molasses, while dark brown sugar contains about 6.5% molasses. Brown sugar can also come in various forms, such as coarse or soft, depending on its moisture content, which can be modified through different processing techniques and by adjusting the amount of molasses it contains.

Because brown sugar contains molasses, it has more moisture than white sugar, which is why it behaves differently in baking and can harden over time as the remaining water in the molasses evaporates. Brown sugar adds complexity and big flavor to recipes, and is commonly used in baked goods and desserts.