Flour is any seed or grain ground into a powder. For example, flour can be made from amaranth, arrowroot, barley, buckwheat, chickpea, corn, nuts, oats, potato, quinoa, rice, spelt, tapioca, teff, wheat or rye grains, among others. Flours last about 5 months in a cool, dry place, before oils in the grains make them rancid. Flour should be stored in a cool, dry place. It can also be stored in the refrigerator, or frozen.
Plain flour or all-purpose flour is the most common flour used in Western baking. Usually made from wheat, it has a strong gluten protein content which gives a strong dough and a light and fluffy result
Bread flour can also be called strong flour or hard flour. It is high protein and high gluten, so it traps yeast gas inside as the bread bakes. This makes lots of little holes inside and the bread becomes light and fluffy.
Cake, pastry or soft Flour has a lower gluten content so it is used for lighter bakes such as sponge cake or chiffon cake.
Self-raising flour is plain Flour that has been already sifted with baking powder. It is usually used for cakes or quickbreads such as scones.
Wholemeal/whole wheat flour is healthy flour made from the complete wheat kernel, including the bran and the germ. When used in bread and cakes, it gives a nutty flavor and the cake or bread will not rise as high, so some chefs prefer to use half wholemeal flour and half all-purpose flour. If you prefer to bake with wholemeal flour, replace 1 cup of white flour with 7/8 of a cup of whole flour, as the flour is heavier.
Adapted from The Singapore Women's Weekly.