A lot has changed in the world of flours since I was a child. The shelves that used to hold just all-purpose, bread, and cake flour are now groaning with flours milled from seeds, nuts, and grains. What’s the best way to store all these flours, and how long do they last? We spoke to Susan Reid of King Arthur Flour and Cassidy Stockton of Bob’s Red Mill, and they helped us compile this guide on the different categories of flours, where to store them, and their shelf lives.