To create free-motion machine embroidery, the embroiderer runs the machine and skillfully moves tightly hooped fabric under the needle to create a design. The "feed dogs" or machine teeth are lowered or covered, and the embroiderer moves the fabric manually. The embroiderer develops the embroidery manually, using the machine's settings for running stitch and fancier built-in stitches. In this way, the stitches form an image on a piece of fabric. An embroiderer can produce a filled-in effect by sewing many parallel rows of straight stitching. A machine's zigzag stitch can create thicker lines within a design or be used to create a border. Many quilters and fabric artists use a process called thread drawing (or thread painting) to create embellishments on their projects or to create textile art.