Silk is a natural protein fibre produced by the silkworm caterpillar as it wraps its cocoon; the single fine, continuous thread of a cocoon can reach hundreds of metres. For centuries silk was the most expensive fabric and the engine of the entire Silk Road. Its virtues are almost fabulous: it is strong at low weight, soft, pleasantly cool in summer and warm in winter, has a natural noble sheen and drapes beautifully. It is made into evening and bridalwear, blouses, dresses, lingerie and scarves. Silk is demanding: it fears direct sun, perspiration and high heat, and needs gentle or dry care.