Fiber is a long, thin strand or thread of material. Fibers are flexible and may be spun into yarn and made into fabrics. Many of the fibers are colored before they become filaments, thus they are difficult to dye after the fiber is woven into a fabric. Fibers naturally occur in both plants and animals. More than half of the fibers produced are natural fibers; they include cotton, hair, fur, silk, and wool. While other fibers are manufactured. There are two types of manufactured fibers: synthetic fibers and regenerated fibers. Synthetic fibers are made entirely from chemicals whereas regenerated fibers are made from natural materials. The principal use of fibers is in the manufacture of textile yarns and ultimately textile fabrics. Most textile fibers are slender, flexible, relatively strong structures that are elastic in that they stretch when put under tension and partially or completely return to their original length when the tension is removed.