Silk is a natural fibre made by the silk worm cocoon. Silk fibres are very strong and are often used to make cloth.
The cloth from silk can be made into rugs, bedding, or can be used to write or paint on. In the past, silk was used to make parachutes. The practice of growing silkworms for silk production is called sericulture.
Most spiders make a natural fibre of their own that is also called silk.