The heald is a device that controls the warp or longitudinal threads during the weaving process. When weaving on the simplest loom, one person manually manipulates the weft or cross threads above and below the warp threads. On more
complex looms, healds control the warp.

Weaving healds can be divided into silk healds and healds. The healds used in shuttle looms are mostly nylon healds and steel wire healds. Flat healds are used for shuttleless looms, and healds are the way for warp yarns to enter the
weaving process. Therefore, warp yarns have strict requirements on the technical performance of the weaving heddle.

The entire assembly of the heddle and its frame is the heddle shaft or wire harness. When the weaver lifts the wire harness, the warp yarns controlled by the healds rise to form a shed or open space for the weft yarns to pass through.