The single needle lock stitch is achieved using a sewing machine equipped with a needle and a bobbin. The process begins when the needle pierces the fabric, carrying the upper thread down into the fabric layers. As the needle goes down, the bobbin, which is located underneath the fabric, rotates. The upper thread wraps around the bobbin thread, forming a stitch. When the needle pulls back up, the thread tightens, securing the stitch in place.