Tapestry threads, also known as wefts, are the horizontal threads that are woven into the vertical warp threads to create a tapestry. Wefts are usually made of wool, silk, or cotton and are used to create intricate patterns and designs. The wefts are woven in and out of the warp threads, creating a strong and durable fabric. Tapestry threads are an essential part of the tapestry weaving process and are used to create beautiful and unique pieces of art.