Picking the Right Flour for the Job

In most grocery stores you'll see many types of white wheat flours: all-purpose, cake,  bread, self-rising (if you are in the South), and sometimes pastry. Less common are the whole wheat varieties -- you can usually find whole wheat all-purpose flour easily, but whole wheat pastry flour and whole wheat bread flour are harder to come by. When I was growing up, we usually had all-purpose white flour, self-rising white flour, and cake flour on hand. The cake flour was always Swans Down, and the others were nearly always White Lily. I never heard of bread flour or pastry flour until I was grown! So ... what distinguishes these types of flours, and why should you care?

Missing: The bag of unbleached all-purpose white flour I have; it was way in the back of the
flour/cornmeal/sugar cabinet. Yes, I have an entire 2-door cabinet devoted to baking supplies.