Tightly twisted yarn consisting of several strands that has a circular cross-section and is used in commercial and home sewing machines and for hand sewing. Thread is usually wound on spools, with thread size (degree of fineness) indicated on the spool end. Cotton thread can be used with fabrics made from yarn of plant origin, such as cotton and linen, and with rayon (made from cellulose, a plant substance). Silk thread is suitable for silks and wools, both of animal origin. Nylon and polyester threads are appropriate for synthetics and for knits with a high degree of stretch.