Fibers are threads or yarns made to produce other materials. Usually, they are knitted or woven into fabrics; however, products such as paper and fiberglass are also made of fibers.
In terms of fabrics, most fibers fall under one of two categories: natural or synthetic. Natural fibers come from plant or animal sources such as cotton, flax, sheep’s wool or silkworm cocoons. Manufacturers can spin these materials into threads without having to alter them in any major way.
Synthetic fibers come from manmade processes and chemicals. Fibers such as polyester and nylon are made of chemical polymers spun into threads. However, some synthetic fibers come from natural sources. For example, modal and rayon come from wood cellulose that uses chemical processes to convert wood into fiber.