One strand of yarn is referred to as a single ply yarn. If we take two of these yarns and twist them together this creates a double, or 2-ply yarn. For very fine materials such as silk, it is not unusual to have a 36-ply yarn. The greater the number of ply a yarn has, the stiffer it will be: however with very soft yarns - bamboo, for example - having a 36-ply yarn may still result in a softer final rope than a single ply jute rope. For Shibari, hemp rope tends to be made from 1-ply yarn, whilst jute rope is made from either 1- or 2-ply. Both of these options have advantages and disadvantages. Double ply rope is slightly stiffer than single ply, and not quite as strong. It is however resistant to abrasion, and less prone to high-stranding. Some people have a preference for the appearance of 1-ply rope, while others struggle to spot the difference.
