After the loom is set up, the warp (or vertical) threads are tied on the loom. These are the threads that eventually become the fringe of the rug. The weft runs horizontally and intertwines with the warp to create the foundation of the rug. The weft also creates the selvedges (or edges) of the rug, which hold the rug together. The knots, made of wool or silk, are then tied to the warp threads. The weaver uses a knife (or a hook) to cut the knot, ties the knot with his or her hands, and finishes the process by securing and tightening the knot with a comb-like tool. An experienced weaver can tie one knot every two seconds.