Coir is a product of the coconut tree, Cocos nucifera, and it is sometimes known as coco fiber. The substance is extracted from the hairy husk of coconuts, and used to create a variety of products such as mats, carpets, upholstery stuffing, and brushes. Coir, pronounced KOY-er, is a very coarse, stiff fiber, and it is also extremely resistant to rot and salt water, making it an ideal material for situations in which other fibers would decay.

The word comes from a Malayalam word, kayar, which is derived from kayaru, which means “to be twisted.” The Malayalam language is spoken in Southern India, particularly in the state of Kerala. The language is related to Tamil, Kota, and Tulu, among many other languages spoken in that region. For English speakers interested in trivia, “Malayalam” is among the longest palindromes in the English language, meaning that it reads the same backwards and forwards.

India and Sri Lanka are the two biggest exporters of coir, accounting for most of the world's supply of the substance. To process coir, coconuts are split so that the stiff fibers are accessible. The outer husk is soaked to separate the fibers, which are sorted out into long fibers suitable for use as brush bristles, and shorter fibers which are used to make things like the padding inside inner coil mattresses. After soaking, the fibers are cleaned and sorted into hanks which may later be spun into twine, matted into padding, or used as individual bristles. Coir takes dye well, and many producers dye coir fiber before export.

There are two primary types of coir. The first type, known as white fiber, is extracted from young coconuts. The white fiber is somewhat finer and more pale in color than coir from mature coconuts. This type of coir is often woven into yarn which is used to make mats, sacking, rope, and twine. In rope manufacturing, white coir fiber can sometimes be cheaper than other rope ingredients. Brown fiber, the other type of coir, is from mature coconuts, and it tends to be more stiff and unyielding.

Many Westerners are familiar with coir in the form of stiff doormats, which can be left out in all weathers because of coir's rot resistance. Coir matting can also be found inside some upholstered products, and a close inspection of an inner spring mattress may also yield coir matting, depending on when and where the mattress was made. Coir matting is also sometimes made available in the form of a substrate for plants, since it can be impregnated with water and seeds to sprout flowers and groundcover. The matting will keep weeds back while the plants establish themselves.