Fiber, also spelled fibre,'s a class of materials that're continuous filaments or are in discrete elongated pieces, similar to lengths of thread. They're 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 s, 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. Synthetic fibe… (More on Fiber)