One of the main raw materials used in the production of synthetic fibres is crude oil. The crude oil is first distilled, which creates the substances that the various fibres used in the textile industry are derived from. These resulting synthetic fibres can be used either alone or in combination with natural fibres such as cotton, wool and linen. For example, one method for manufacturing synthetic textile fibres is through a process that produces resins which, once spun and solidified, become flexible, light and strong. One of the most common synthetic fibres is polyester.