Yarn is a long continuous length of interlocked fibres, suitable for use in the production of textiles, sewing, crocheting, knitting,weaving, embroidery, and ropemaking. Thread is a type of yarn intended for sewing by hand or machine. Modern manufactured sewing threads may be finished with wax or other lubricants to withstand the stresses involved in sewing. Embroidery threads are yarns specifically designed for hand or machine embroidery. It often used in made cloth and woven labels.

The most common plant fiber is cotton, which is typically spun into fine yarn for mechanical weaving or knitting into cloth woven labels. The most commonly used animal fiber is wool harvested from sheep. For hand knitting and hobby knitting, thick, wool yarns are frequently used.

Other animal fibers used include alpaca, angora, mohair, llama, cashmere, and silk. More rarely, yarn may be spun from camel, yak,possum, qiviut, cat, dog, wolf, rabbit, or buffalo hair, and even turkey or ostrich feathers. Natural fibers such as these have the advantage of being slightly elastic and very breathable, while trapping a great deal of air, making for a fairly warm fabric.

Other natural fibers that can be used for yarn include linen and cotton. These tend to be much less elastic, and retain less warmth than the animal-hair yarns, though they can be stronger in some cases. The finished product will also look rather different from the woollen yarns. Other plant fibers which can be spun include bamboo, hemp, corn, and soy fiber.

Yarn may be used undyed, or may be coloured with natural or artificial dyes. It change price, like more color you use, more higher price woven labels will be.Most yarns have a single uniform hue, but there is also a wide selection of variegated yarns:

• Heathered or tweed: yarn with flecks of different coloured fiber

• Ombre: variegated yarn with light and dark shades of a single hue

• Multicolored: variegated yarn with two or more distinct hues (a "parrot colourway" might have green, yellow and red)

• Self-striping: yarn dyed with lengths of color that will automatically create stripes in a knitted or crocheted object

• Marled: yarn made from strands of different-colored yarn twisted together, sometimes in closely related hues