Wool is the fiber derived from the hair of some animals, usually sheep. It has two qualities that distinguish it from hair or fur: it is scaled in such a way that helps the animal move out burrs and seeds that might embed themselves into its skin; and it is crimped, in some fleeces more than 20 bends for every few centimeters.
It is possible possible to spin and felt the fleece. They help the individual fibers "grab" each other so that they stay together. They also make the product retain heat, as they trap heat in their bends.
Wool is processed into clothing, carpeting, felt, and padding. As the raw material has been readily available since the widespread domestication of sheep and similar animals, the use of wool for clothing and other fabrics dates back to some of the earliest civilizations. Wool takes dye easily.