A cotton gin—meaning "cotton engine"—is a machine that quickly and easily separates cotton fibers from their seeds, enabling much greater productivity than manual cotton separation. The separated seeds may be used to grow more cotton or to produce cottonseed oil. Handheld roller gins had been used in the Indian subcontinent since around 500 A.D. and later in other regions. The Indian worm-gear roller gin was invented sometime around the 16th century and has, according to Lakwete, remained virtually unchanged today.