A "4-thread" refers to a type of sewing or embroidery thread that consists of four individual strands twisted together. This construction provides added strength and durability, making it suitable for various sewing projects, including quilting and garment making. The thickness and texture of 4-thread can vary, allowing for different applications in crafting. In the context of sewing machines, a 4-thread overlock stitch is commonly used to finish edges and prevent fraying. This technique utilizes four threads to create a secure and professional-looking seam, often employed in apparel manufacturing and home decor projects.