All-purpose flour is a versatile type of flour that is suitable for all types of baked goods, from pizza dough to breads, pie crusts, cakes, cookies, and more. It is a medium-strength, medium-gluten flour that is made from a blend of hard and soft wheats, typically at an 80:20 ratio. The gluten content of all-purpose flour is usually around 10 to 12 percent, which is lower than bread flour but higher than cake flour. All-purpose flour is a blend of strong and weak flours formulated to be acceptable for making crusty breads as well as delicate pastries and cakes. It is a decent middle-of-the-road flour that can be used for most purposes, such as baking, cooking, coating meats and vegetables, and as a thickening agent for sauces and gravies.

To understand what all-purpose flour is, it is important to know that different strains of wheat are naturally higher in protein than others, and the higher-protein ones are said to be "hard." Low-protein wheats are said to be "soft." Durum wheat, which is used for making pasta, is the hardest, or highest-protein wheat, while soft white wheat is the softest. All-purpose flour is a blend of hard and soft wheats, which makes it a versatile flour that can be used for a wide range of baked goods.

It is worth noting that all-purpose flour is not the same as self-rising flour, which has baking powder and salt added to it. Additionally, there are other types of flour, such as bread flour, cake flour, and pastry flour, that are formulated for specific purposes.