It is the knotting, or tying of the colored yarn around the threads of the foundation that creates the pile of a carpet. The most important factor in the creation of a quality rug is its basic construction and the integrity of its principal materials. Knotting is a very precise skill and it is the major factor in the look of a finished carpet. The pile is formed from various types of knots; the most common of which are symmetrical and asymmetrical.