Tapestry is a form of textile art which was traditionally woven by hand on a loom. Normally it is used to create images rather than patterns. Tapestry is relatively fragile, and difficult to make, so most historical pieces are intended to hang vertically on a wall, or sometimes to lie horizontally over a piece of furniture such as a table or bed. Some periods made smaller pieces, often long and narrow and used as borders for other textiles. Most weavers use a natural warp thread, such as wool, linen, or cotton. The weft threads are usually wool or cotton but may include silk, gold, silver, or other alternatives.