Chain stitches catch a loop of the thread on the surface of the fabric. In the simplest of the looped stitches, the chain stitch, the needle comes up from the back of the fabric and then the needle goes back into the same hole it came out of, pulling the loop of thread almost completely through to the back; but before the loop disappears, the needle come back up (a certain distance from the beginning stitch -the distance deciding the length of the stitch), passes through the loop and prevents it from being pulled completely to the back of the fabric. The needle then passes back to the back of the fabric through the second hole and begins the stitch again.