Fibers come from both natural and synthetic sources. Natural fibers include plant fibers like cotton and jute, and animal fibers like wool and silk. Cotton is obtained from cotton plants and is best grown in black soil and warm climates. It is ginned to separate cotton seeds from fibers. Jute comes from jute plant stems and is harvested when the plant is flowering. Wool is obtained by shearing the fleece of sheep and other animals, then scouring and sorting the different hair types. Silk is produced by silkworms feeding on mulberry leaves. Fibers are spun into yarns then woven or knitted into fabrics using various machines.