The coats of domestic dogs are of two varieties: "double" getting popular in dogs (along with wolves) originating from colder climates, created up of the coarse guard hair and a delicate down hair, or "single", with the topcoat only. Breeds could possibly have an occasional "blaze", stripe, or "star" https://dogs11986.madmouseblog.com/12242954/dogs-things-to-know-before-you-buy