There are two plants and three types of webs that can be turned into thread. Thread can then be woven into cloth, which then can be used to create a variety of textile products such as bags, clothing, rope or crafts. (For a full discussion of the process and possibilities, see clothing industry.)
Animal hair that is produced from a butchered animal can also be spun into yarn thread at a farmer's workshop using the "Spin Thread" order, but cannot be used for the production of cloth or related items.
A dwarf with the thresher labor enabled can process plants (either rope reeds or pig tails) into thread at a farmer's workshop with the "Process Plants" job order. With a loom, any dwarf with the weaver labor enabled will automatically collect any spider* silk webs that are on the ground, turning them into thread.
Any thread can also be used at a Hospital to treat the wounded by suturers. This is the only use of threads made from the hair of non-shearable creatures, as they cannot be spun into yarn.