Spinning is described as the process of drawing and twisting fibers together to produce thread or yarn. Likewise, it is the process of converting fibres into yarn.

The fibres may be natural fibres such as cotton or manmade fibres such as polyester. Sometimes, the term spinning is also used for production of manmade filament yarn (yarn that is not made from fibres). Whatsoever is the case, the final product of spinning is yarn.

-see also:
"Spinning" is in the NAICS Code "313111"
  (Yarn Spinning MillsCrochet spun yarns (e.g., cotton, manmade fiber, silk, wool) made from purchased fiber)