An overlock machine is a specialized sewing machine designed to sew over the edge of fabric to prevent fraying and create a clean finish. It uses multiple threads and a unique stitch formation, allowing it to trim the fabric while sewing, which is particularly useful for knit and stretch fabrics. These machines are commonly used in the garment industry and by home sewers for making garments, hems, and seams. They can also create decorative edges and are often used in conjunction with other sewing machines, such as a sewing machine, to achieve professional-quality results.