The most time consuming, labor intensive way to produce a rug in which individual yarns are knotted around pair of warp yarns that run the length of the rug. In general, the more knots per square inch, the more durable and valuable the rug is. There are two: Persian and Turkish. The Persian knot is asymmetric and open to either the right of the left, while the Turkish knot is symmetric. kinds of knots that can be used