The process of quilting uses a needle and thread to join two or more layers of material together to make a quilt. Typical quilting is done with three layers: the top fabric or quilt top, batting or insulating material and backing material. The quilter's hand or sewing machine passes the needle and thread through all layers and then brings the needle back up. The process is repeated across the entire piece where quilting is wanted. A straight or running stitch is commonly used and these stitches can be purely functional or decorative and elaborate. Quilting is done on bed spreads, art quilt wall hangings, clothing, and a variety of textile products. Quilting can make a project thick, or with dense quilting, can raise one area so that another stands out.