Once a luxury only the extremely affluent could afford, sugar was called "white gold" because it was so scarce and expensive. Although Persia and ancient Arabia were cultivating sugar in the 4th century B.C., the Western World didn't know of it until the 8th century when the Moors conquered the Iberian peninsula. Early sugar wasn't the granulated alabaster substance most of us know today. Instead, it came in the form of large solid loaves or blocks ranging in color from off-white to light brown. Chunks of this rock-hard substance had to be chiseled off and ground to a powder with a mortar and pestle. Modern-day sugar is no longer scarce or expensive and comes in myriad forms from many origins. Sugar cane and sugar beets are the sources of most of today's sugar, also known as sucrose (which also comes from maple sap maple sugarand sorghumdextrose (grape or corn sugar), fructose (levulose), lactose (milk sugar) and maltose (malt sugar). The uses for sugar are countless. Besides its sweetening value, sugar adds tenderness to doughs, stability to mixtures such as beaten egg whites for meringue, golden-brown surfaces to baked goods and, in sufficient quantity, it contributes to the preservation of some foods. Granulated or white sugar is highly refined cane or beet sugar. This free-flowing sweetener is the most common form both for table use and for cooking. Granulated sugar is also available in cubes or tablets of various sizes, as well as a variety of textures. Superfine sugar, known in Britain as castor (or caster) sugar, is more finely granulated. Because it dissolves almost instantly, superfine sugar is perfect for making meringues and sweetening cold liquids. It can be substituted for regular granulated sugar cup for cup. Powdered or confectioners' sugar is granulated sugar that has been crushed into a fine powder. To prevent clumping, a small amount (about 3 percent) of cornstarch is added. Powdered sugar must generally be sifted before using. Because it dissolves so readily, it's often used to make icings and candy. It's also used decoratively, as a fine dusting on desserts. One and three-quarters (packed) cups powdered sugar equals 1 cup granulated sugar. Powdered sugar is called icing sugar in Britain and sucre glace in France. Decorating or coarse sugar (also called sugar crystals or crystal sugar) has granules about four times larger than those of regular granulated sugar. It's used for decorating baked goods and can be found in cake-decorating supply shops and gourmet markets. Rock candy is an even larger form of sugar crystals. Colored sugar, also used for decorating, is tinted granulated sugar and can be found in several crystal sizes. Flavored sugar is granulated sugar that's been combined or scented with various ingredients such as cinnamon or vanilla. All granulated sugar can be stored indefinitely if tightly sealed and kept in a cool, dry place. Today's brown sugar is white sugar combined with molasses, which gives it a soft texture. The two most commonly marketed styles of brown sugar are light and dark, with some manufacturers providing variations in between. In general, the lighter the brown sugar, the more delicate the flavor. The very dark or "old-fashioned" style has a more intense molasses flavor. Brown sugar is usually sold in 1-pound boxes or plastic bagsthe latter help the sugar retain its moisture and keep it soft. Hardened brown sugar can be resoftened by placing it with an apple wedge in a plastic bag and sealing tightly for one to two days. A firmly packed cup of brown sugar may be substituted for 1 cup granulated sugar. Both free-pouring and liquid brown sugar are also now available. Neither of these forms should be substituted for regular brown sugar in recipes. Though similar in color, brown sugar should not be confused with raw sugar, the residue left after sugarcane has been processed to remove the molasses and refine the sugar crystals. The flavor of raw sugar is akin to that of brown sugar. In this raw state, however, sugar may contain contaminants such as molds and fibers. The so-called raw sugar marketed in the United States has been purified, negating much of what is thought to be its superior nutritive value. Two popular types of raw sugar are the coarse-textured dry Demerara sugar from the Demerara area of Guyana, and the moist, fine-textured Barbados sugar. Turbinado sugar is raw sugar that has been steam-cleaned. The coarse turbinado crystals are blond colored and have a delicate molasses flavor. Other sources of sugar include maple sap, palm sap and sorghum. Almost 100 percent of sugar is carbohydrate. Granulated white sugar contains about 770 calories per cup, as does the same weight (which equals about 2 cups) of powdered sugar. A cup of brown sugar is slightly higher at 820 calories. It also contains 187 milligrams of calcium, 56 of phosphorous, 4.8 of iron, 757 of potassium and 97 of sodium, compared to only scant traces of those nutrients found in granulated sugar. Artificial sweeteners such as aspartame and saccharin are essentially calorie-free and are used as a sugar substitute both commercially and by the home cook. Sugar also comes in syrup form, the most common being cane syrup, corn syrup, golden syrup, honey, maple syrup, molasses, sorghum and treacle.