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 fibers are then processed into various cotton goods such as calico and canvas, while any undamaged cotton is used largely for textiles like clothing. The separated seeds may be used to grow more cotton or to produce cottonseed oil.

Cotton is a soft, fluffy staple fiber that grows in a boll, or protective case, around the seeds of the cotton plants of the genus Gossypium in the mallow family Malvaceae. The fiber is almost pure cellulose, and can contain minor percentages of waxes, fats, pectins, and water. Under natural conditions, the cotton bolls will increase the dispersal of the seeds.