Fiber (also spelled fibre) is a class of materials that are continuous filaments or are in discrete elongated pieces, similar to lengths of thread. A fiber is an elongated tapering thick-walled plant cell that imparts elasticity, flexibility, and tensile strength. They are very important in the biology of both plants and animals, for holding tissues together.
Human uses for fibers are diverse. They can be spun into filaments, string, or rope, used as a component of composite materials, or matted into sheets to make products such as paper or felt. Fibers are often used in the manufacture of other materials. The strongest engineering materials are generally made as fibers, for example carbon fiber and Ultra-high-molecular-weight polyethylene.
Synthetic fibers can often be produced very cheaply and in large amounts compared to natural fibers, but for clothing natural fibers can give some benefits, such as comfort, over their synthetic counterparts.