Most handmade rugs are woven by tying knots on the warp strands. All of the different types of knots have a knot collar, the portion that wraps around the warps, and the ends that make up the pile.

• Ghiordes or Turkish knots are symmetrical with both ends of the yarn pulled up between two warps and the knot collar wrapping around two warps.

• Senneh or Persian knots are asymmetrical with the ends pulled through singly between each pair of warps and a knot collar around every other warp.

• Jufti knots are symmetrical or asymmetrical, but are wrapped around pairs of warps rather than single warps. This method makes the pile less dense and weavers can produce them faster.

• Spanish knots are symmetrical and knotted around every other single warp.

To determine the knot used in an Oriental rug, turn the rug over and examine the construction. You will see thousands of squarish-shaped, tiny loops that are the part of the knots as they wrap around the warp threads. With Ghiordes knots, two loops or bumps are visible across the warp where the knot is tied. The Senneh knot has only a single, visible loop. If a Jufti knot is used, the knot count will be half or less of the warp count.

Knot density is the number of knots per square inch and can be a factor in a carpet's value. It is generally not a factor in nomadic or village rugs, but important in rugs produced in workshops. Nomadic people and villagers lack the sophisticated tools of city weavers. Their rugs' values lie in designs created from memory, the use of natural materials and dyes, and their expressions of a way of life. These rugs generally have a knot density of between 25 to 100 knots per square inch. Rugs with a higher knot density take a longer time to make. As nomads migrate with the seasons, they must carry their looms if their rugs are not completed when it is time to migrate. Thus, these rugs generally have a lower knot density. Their value is in their heritage and artistic merit.

Knot density is an important factor in rugs produced in workshops. They have more sophisticated tools and follow drawings on squared paper called cartoons. Precision in design increases their value. They have a density of between 100 to more than 1,000 knots per square inch. They are usually made of silk on a silk foundation, because silk allows more knots to be tied than with cotton or wool. The greater the density, the more intricate the design can be. Knot density does not increase durability, but allows more elaborate designs.

Every knot is hand tied, and a skilled weaver can tie a knot in 10 seconds. Using this standard, a 9 by 12 foot rug with a density of 150 knots per square inch takes 6,480 hours to make – or approximately two and a half years of normal working hours. If the knot density is higher, the time increases accordingly. Most workshop carpets are woven by two or three weavers working together so they can be completed faster and sold more quickly.

Knot density varies greatly in Oriental rugs depending on the region they were woven, the age of the rug, the design and the construction. To untrained people, determining knot count can be tricky, and knot counts are often misrepresented on purpose to increase the price or because the seller is untrained in this esoteric skill. When considering the value and investment potential an Oriental rug, it is best to seek out the experts such as Landry & Arcari Rugs and Carpeting. The experts in this family owned business will help you select your dream carpet – or design and weave it for you.