Pastry flour: Pastry flour is perfect for making quick breads like muffins, banana bread, waffles, and pancakes. Its protein percentage is usually about 6% to 8%.
High-gluten flour: This flour is typically only available to commercial bakers or via mail order from places like King Arthur Flour. Its protein level is usually greater than 14%. It’s used in bagels (it gives them their tasty chewy texture) and breads with a high percentage of rye.
Fancy durum flour. Also known as semonlina flour (though ground finer) or pasta flour, durum flour is made from durum wheat. Though high in protein, durum flour does not contain enough gluten to make good bread unless mixed in with regular wheat flour.
00 flour. 00 is an Italian designation for a type of flour commonly used in pizza crust. It is softer (lower in protein) than American bread or all purpose flour.
Spelt flour: Spelt, which is also known as farro, is an ancient grain that is a cousin to wheat. It contains enough gluten to make a light loaf of bread, but absorbs less water than wheat, and so requires a lower hydration. The gluten is also somewhat less resiliant than that of wheat, and, as such, one needs to be careful when using a mixer, as it's easy to over-develop.