Couching is a fun way to add different textures and elements to your embroidery, as this stitch essentially involves sewing another fibre/thread on to your design. It is the stitch to use when you want to add a piece of wool or string which would be too thick to sew through your fabric.
You can create extra interest and detailing by using contrasting colours between the fibre being attached and the thread used to attach the fibre. (which judging from the photos is what I should have done so you could see the stitches better!)some lovely texture to your piece.