In the textile arts, plying is a process use to create a strong, balanced yarn. It is done by taking two or more strands of yarn that each have a twist to them and putting them together. The strands are twisted together, in the opposite direction than that in which they were spun. When just the right amount of twist is added, this creates a balanced yarn, which is a yarn with no tendency to twist upon itself. Almost all store bought yarns are balanced, plied yarns.