Fur is a synonym for hair, used in reference to non-human animals, usually mammals, particularly those with extensive body hair coverage. The term is sometimes used to refer to the body hair of an animal as a complete coat, also known as the "pelage". Fur is also used to refer to animal pelts which have been processed into leather with the hair still attached, as is the custom in the making of fur coats in certain fashion trends. The words fur or furry are also used, more casually, to refer to hair-like growths or formations; particularly when the subject being referred to exhibits a dense coat of fine, soft "hairs."
Animal fur, if layered, rather than grown as a single coat, may consist of short ground hair, long guard hair, and, in some cases, medium awn hair. Mammals with reduced amounts of fur are often called "naked", as in The Naked Ape, naked mole rat, and naked dogs.
An animal with commercially valuable fur is known within the fur industry as a furbearer. The use of fur as clothing and/or decoration is considered controversial by some people: most animal rights advocates object to the trapping and killing of wildlife, and to the confinement and killing of animals on fur farms.
Fur has been a major challenge for 3D computer graphics artists due to its visual complexity and physical properties. The first movie which made extensive use of CGI fur was Pixar's 2001 film Monsters, Inc..
Nature of fur 
Fur usually consists of two main layers:
- Ground hair (known also as undercoat or down hair) — the bottom layer consisting of wool hairs, usually wavy or curly without straight portions or sharp points; down hairs tend to be shorter, flat, curly, and more numerous than the top layer. Its principal function is thermoregulation; it maintains a layer of dry air next to the skin and repels liquid water, thus providing thermal insulation.
- Guard hair — the top layer consisting of longer, generally coarser, nearly straight shafts of hair that stick out through the underfur. The distal ends of the guard hairs provide the externally visible layer of the coat of most mammals with well-developed fur. This zone of the coat displays the most marked pigmentation and gloss, including coat patterns adapted to display or camouflage. It also is adapted to shedding water and blocking sunlight, protecting the undercoat and skin from outside factors, such as rain and ultraviolet. Many animals such as cats erect their guard hairs as part of their threat display when agitated.
As a rule, mammals with well-developed down hairs and guard hairs also have large number of awn hairs; awn hairs begin their growth much as guard hairs do, but change their mode of growth, usually when less than half the length of the hair has emerged. This portion of such a hair is the so-called awn. The rest of the growth is thin and wavy, much like down hair. In many species of mammals the awn hairs comprise the bulk of the visible coat. The proximal part of the awn hair shares the function of the down hairs, whereas the distal part aids the water-shedding function of the guard hairs, though their thin basal portion prevents their being erected like true guard hairs.
Use in clothing 
In clothing, fur is leather with the hair retained for its insulating properties. Fur has long served as a source of clothing for hominoids including the Neanderthal. Animal furs used in garments and trim may be dyed bright colors or to mimic exotic animal patterns, or shorn down to imitate the feel of a soft velvet fabric. The term "a fur" is often used to refer to a fur coat, wrap, or shawl.
Usual animal sources for fur clothing and fur trimmed accessories include fox, rabbit, mink, beavers, ermine, otters, sable, seals, cats, dogs, coyotes, chinchilla, and possum. The import and sale of seal products was banned in the U.S. in 1972 over conservation concerns about Canadian seals. The import and sale is still banned even though the Marine Animal Response Society estimates the harp seal population is thriving at approximately 8 million. The import, export and sales of domesticated cat and dog fur were also banned in the U.S. under the Dog and Cat Protection Act of 2000.
The manufacturing of fur clothing involves obtaining animal pelts where the hair is left on the animal's processed skin. In contrast, making leather involves removing the hair from the hide or pelt and using only the skin. The use of wool involves shearing the animal's fleece from the living animal, so that the wool can be regrown but sheepskin shearling is made by retaining the fleece to the leather and shearing it. Shearling is used for boots, jackets and coats and is probably the most common type of skin worn.
Most animal rights activists are opposed to the trapping and killing of wildlife, and the confinement and killing of animals on fur farms. According to Humane Society International, over 8 million animals are trapped yearly for fur, while more than 30 million were raised in fur farms. According to Statistics Canada, 2.6 million fur-bearing animals raised on farms were killed in 2010. Another 700,000 were killed for fur by traps. Based on a controversial animal rights video, the People for the Ethical Treatment of Animals (PETA) allege that fur farming in China is particularly inhumane.
See also 
- Human activities
- "Harp Seal", Marine Animal Response Society.
- Rules and Regulations Under the Fur Products Labeling Act.
- Australian Wool Corporation, Australian Wool Classing, Raw Wool Services, 1990.
- Chamber's journal, Published by Orr and Smith, 1952, pg 200, Original from the University of Michigan.
- Humane Society International Fur Trade.
- "Fur production, by province and territory", Statistics Canada.
- China's Shocking Dog and Cat Fur Trade