Detail of the Bayeux Tapestry showing fillings in laid work.
In embroidery, couching and laid work are techniques in which yarn or other materials are laid across the surface of the ground fabric and fastened in place with small stitches of the same or a different yarn.
The couching threads may be either the same color as the laid threads or a contrasting color. When couching threads contrast with laid threads, patterns may be worked in the couching stitches.
In couching, one or more threads are laid on the fabric surface and sewn to the fabric at regular intervals.
In couched filling, threads are laid on the surface in a trellis pattern and sewn to the fabric at the intersections.
In laid work or Bayeux stitch, threads are laid side-by-side to fill a shape, then held in place with a thread at right angles to the laid threads. This crossing thread is then couched to the fabric to hold the laid threads in place.
In Bokhara couching or Bokhara stitch, the couched threads are held in place with many tiny crossing stitches, which may be aligned from row to row to produce patterns.,
In Roumanian stitch, long satin stitches are each held in place with a small diagonal stitch made in the center
In Roumanian couching, bundles of laid threads are held in place with Roumanian stitches
In Underside couching, a heavy couching thread (historically, a stout linen) is brought up from the wrong side of the work, looped over the laid thread, and returned to the wrong side. The couching thread is then given a sharp pull which draws a small loop of laid thread through to the wrong side of the fabric. Underside couching has the advantages that the couching thread is completely concealed from the front and is not subject to wear.