Bread flour is white flour made from hard, high-protein wheat. It has more gluten strength and protein content than all-purpose flour. It is unbleached and sometimes conditioned with ascorbic acid, which increases volume and creates better texture. This is the best choice for yeast products.

Shelf Life: several months in a cool, dry cabinet when stored in a sealed container or if tightly wrapped, and up to one year in the freezer.

Whole-wheat flour is made from the whole kernel of wheat and is higher in dietary fiber and overall nutrient content than white flours. It does not have as high a gluten level, so often it's mixed with all-purpose or bread flour when making yeast breads. Whole wheat flour is equivalent to British whole meal flour.

Shelf Life: 6 months to one year in the freezer if stored in tightly sealed plastic containers or if tightly wrapped. It will keep for only a few months if stored in a cabinet. Due to the presence of the wheat germ, resulting in an unsaturated oil content that is higher than refined flour. The potential for rancidity is greater if whole-wheat flour is kept for long periods and particularly if it is not stored under refrigerated conditions. It is best to store whole-wheat flour in a tightly sealed container in the refrigerator or freezer.

Instant flour (Wondra from Gold Medal) is granular and formulated to dissolve quickly in hot or cold liquids. It will not work as a substitute for all-purpose flour, although there are recipes on the container for popovers and other baked goods. It is used primarily in sauces and gravies.

Cake flour is a fine-textured, soft-wheat flour with a high starch content. It has the lowest protein content of any wheat flour. It is chlorinated (a bleaching process which leaves the flour slightly acidic, sets a cake faster and distributes fat more evenly through the batter to improve texture. When you're making baked goods with a high ratio of sugar to flour, this flour will be better able to hold its rise and will be less liable to collapse. This flour is excellent for baking fine-textured cakes with greater volume and is used in some quick breads, muffins and cookies. If you cannot find cake flour, substitute bleached all-purpose flour, but subtract 2 tablespoons of flour for each cup used in the recipe (if using volume measuring).

Pastry flour also is made with soft wheat and falls somewhere between all-purpose and cake flour in terms of protein content and baking properties. Use it for making biscuits, pie crusts, brownies, cookies and quick breads. Pastry flour makes a tender but crumbly pastry. Do not use it for yeast breads. Pastry flour (both whole-wheat and regular) is not readily available at supermarkets, but you can find it at specialty stores and online.

Self-rising flour, sometimes referred to as phosphated flour, is a low-protein flour with salt and leavening already added. It's most often recommended for biscuits and some quick breads, but never for yeast breads. Exact formulas, including the type of baking powder used, vary by manufacturer. Recipes that call for self-rising flour do not call for the addition of salt or leavening agents.
Make your own self-rising flour:  Using a dry measure, measure the desired amount of all-purpose flour into a container. For each cup of all-purpose flour, add 1 1/2 teaspoons of baking powder and 1/2 teaspoon of salt. Mix to combine.

Semolina flour is used in making pasta and Italian puddings. It is made from durum wheat, the hardest type of wheat grown. The flour is highest in gluten.

Spelt flour is one of the most popular and widely available non-wheat flours. The full name of spelt is Triticum aestivum var. spelta. Spelt flour has a nutty and slightly sweet flavor similar to that of whole wheat flour. It does contain gluten and is a popular substitute for wheat in baked goods. Check out the article on Spelt Flour - Add Spelt Flour to your Diet for Variety and Nutrition.

Durum flour is finely ground semolina and is grown almost exclusively in North Dakota.

Organic flour is used in the same way as regular flour. It must follow U.S. Department of Agriculture regulations to be labeled "organic." Using this flour is a matter of personal preference.

Gluten flour is usually milled from spring wheat and has a high protein. It is used primarily for diabetic breads, or mixed with other non wheat or low-protein wheat flours to produce a stronger dough structure.