There are two types of hair, definitive and agora. Definitive hair grows to a certain length and then ceases to grow anymore. Angora hair on the other had, will continue to grow until the hair falls out. There are three categories of hair which fall under these types. The first type is guard hair.
Guard hair gives the color and the shape of the animal.
Guard hair can come in spines, stiff and definitive like in porcupines , bristles, long, firm, and angora like a horses mane, or guard hair can be awns, definitive, narrow, and weak at the base. Awns account for most kinds of hair which mammals can have. The second category of hair is called under fur. This type of hair is very thick and short. It can be found in cooridinance with guard hair as an insulator, or can be found alone, for example the wool of a sheep.