When referring to flour, most people mean wheat flour unless they say otherwise. Flours made from other foods include amaranth, barley, buckwheat, millet, oats, quinoa, rice, rye, and triticale.
Wheat flours are classified by the amount of protein they contain. Wheat flours made from soft wheats are relatively low in protein and generally are used for making cakes, cookies, pastries, and crackers. Those flours made from hard wheats are high in protein and generally are used for quick and yeast breads.
You can replace part of the all-purpose flour with whole wheat flour. Use proportions of half all-purpose flour and half whole wheat flour in most baked goods. The end product will not look the same and may have less volume and a coarser texture.
Store all-purpose flour in an airtight container in a cool, dry place for 10 to 15 months; store whole grain flours for up to 5 months. For longer storage, refrigerate or freeze the flour in a moisture- and vaporproof container. Before using a refrigerated flour in yeast breads, bring it to room temperature so it does not slow the rising of the bread.
You usually can skip the sifting of all-purpose flour. Even though most all-purpose flour is presifted, the flour settles in the bag during shipping. So, it's a good idea to stir through the flour in the bag or canister before measuring to make it lighter. Then gently spoon the flour into a dry measuring cup and level it off with a spatula.
You will need to sift cake flour before measuring it.