The twist is the spiral arrangement of the fibers around the axis of the yarn. The twist binds the fibers together and also contributes to the strength of the yarn. The amount of twist inserted in a yarn defines the appearance and the strength of the yarn. The number of twists is referred to as turns per inch.

The direction of the twist at each stage of manufacture is indicated by the use of letters S or Z in accordance with the following convention.

Yarn Twisting

The twisting of fibers strands are carried out on a roving frame, ring frame, rotor spinning, and DREF spinning machines etc.the delivery package has to be rotated axially to wind the yarn. The twisting and winding operations are separated in the open-end spinning. However, this is not possible on a roving frame or a ring frame.