Fibers are the most basic raw material for the textile industry. They are thread like strands which are converted into yarns with the help of textile spinning machines. Fibers are divided into various categories on the basis of different criteria. The most common categorization is that of natural fibers and synthetic fibers. Natural fibers have their source in plants and animals and include such fibers as cotton, hemp, linen, jute, silk, wool etc. Synthetic fibers are chemically composed, mostly with petroleum based products and include such fibers as polyester, acrylics, aramid, polyethylene, spandex etc. Fibers are also categorized as filament and staple fibers. Fibers in the form of strands are called filaments, example being nylon filament yarn. Very short fibers are known as staple fibers.