Wool is taken from animals in the Caprinae family, principally sheep, but the hair of certain species of other mammals is also sometimes called "wool", including cashmere from goats, mohair from goats, vicuña, alpaca, and camel from animals in the camel family, and angora from rabbits.

Wool has several qualities that distinguish it from hair or fur: it is crimped, it has a different texture or handle, it is elastic, and it grows in staples (clusters).

The high initial cost and the cost of care of wool garments and wool furnishings has encouraged its substitution by acrylic, polyester or wool/synthetic blends in many products. However, wool’s properties are not equaled by any manufactured fiber: ability to be shaped by heat and moisture, good moisture absorption without feeling wet, excellent heat retention, water repellency, feltability and flame retardancy. Wool was one of the earliest fibers to be spun into yarns and woven into cloth and was one of the most widely used textile fibers before the Industrial Revolution. 

Uses – The most important use of wool is for adult apparel. Wool suits perform well and look great. They fit well because they can be shaped through tailoring. The durable fabrics drape well. They are comfortable under a variety of conditions and retain their appearance during wear and care. Suits are usually dry-cleaned to retain their appearance and shape. Suit materials are also made of synthetic fiber/wool blends.

Even though the amount of wool used in furnishings is low, wool constitutes the standard by which carpet appearance is judged. A major use of wool is in carpets and custom rags, often special order or one-of-a- kind. Wool rugs can be machined-woven, hand-woven or hand-hooked. They are more expensive than those made from other fibers because the rich color, texture and appearance of wool are appreciated and valued. Wool carpets and rugs account for less than one-fifth of the floor coverings market.

Both wool and wool blends are used in upholstery because of their aesthetic characteristics, good appearance retention, durable nature, and natural flame resistance. For residential use no additionally flame retardant treatment is necessary but for many commercial and contract uses wool and wool blend upholstery fabric may require a flame retardant finish.

Handcrafted wall hangings and woven tapes-tries are often made of wool because textile artists like the way the fiber handles. Designers, artists and consumers appreciate the way the finished item looks and wears. Many school laboratories have fire-safety blankets made of wool. Stadium blankets and throws are often made of wool for warmth and an attractive appearance.

In addition to clothing and upholstery, wool has been used for blankets, horse rugs, saddle cloths, felt and wool insulation. Wool felt covers piano hammers, and it is used to absorb odors and noise in heavy machinery and stereo speakers. Ancient Greeks lined their helmets with felt, and Roman legionnaires used breastplates made of wool felt.

Wool has also been traditionally used to cover cloth diapers. Wool fiber exteriors are hydrophobic (repel water) and the interior of the wool fiber is hygroscopic (attracts water); this makes a wool garment able to cover a wet diaper while inhibiting wicking, so outer garments remain dry. Wool felted and treated with lanolin is water resistant, air permeable, and slightly antibacterial, so it resists the buildup of odor. Some modern cloth diapers use felted wool fabric for covers, and there are several modern commercial knitting patterns for wool diaper covers.

Initial studies of woolen underwear have found it prevented heat and sweat rashes because it more readily absorbs the moisture than other fibers.

Merino wool has been used in baby sleep products such as swaddle baby wrap blankets and infant sleeping bags.