Stitch length adjustment is a function on a sewing machine that determines the distance between individual needle penetrations into the fabric. The value is usually given in millimeters and is controlled by a dial or buttons on the machine. Shorter stitches, for example 1 to 2 millimeters long, create stronger and denser seams, suitable for delicate materials or for reinforcing stressed parts of garments. Conversely, longer stitches, typically 4 to 5 millimeters, are used for temporary stitching, known as "basting," or for gathering fabric. The standard length for regular sewing on medium-weight fabrics is approximately 2.5 to 3 millimeters. A zero stitch length means that the fabric does not move and the machine sews in one place, which is used to secure the seam at the beginning and end, known as "backstitching." The choice of the correct length depends on the type of fabric, the thread used, and the purpose of the seam.