Fiber or fibres (see spelling differences) are a class of hair-like materials that are continuous "'filaments"' or are in discrete elongated pieces, similar to pieces of thread. They can be used as a component of composite materials. They can also be matted into sheets to make product such as paper or felt. Fibers are of two types: natural fiber, which consists of animal and plant fibers, and man-made fiber, which consists of synthetic fibers and regenerated fibers. The earliest evidence for humans using fibers is the discovery of wool and dyed flax fibers found in a prehistoric cave in the Republic of Georgia that date back to 36,000 BP.
Natural fibers are made from plant, animal and mineral sources. Natural fibers can be classified according to their origin.
The most used plant fibers are cotton, flax and hemp, although sisal, jute, kenaf, bamboo and coconut are also widely used.
Hemp fibers are mainly used for ropes and aerofoils because of their high suppleness and resistance within an aggressive environment. Hemp fibers are, for example, currently used as a seal within the heating and sanitary industries.
Animal fibers generally comprise proteins such as collagen, keratin and fibroin; examples include silk, sinew, wool, catgut, angora, mohair and alpaca.
After World War II, the build-up of synthetic fibers significantly decreased the use of natural fibers. Now, with the increase of oil prices and environmental considerations, there has been a revival of natural fiber use within the textile, building, plastic and automotive industries. This interest is reinforced by the developmental perspectives on the agro-industrial market and local productions, allowing economic development and independence versus imported materials.