As you guide the fabric ... needle actually has several parts that allow it to attach to the sewing machine and run thread correctly: the butt, shank, shoulder, blade, groove, scarf, eye, and ...
NikolayS [CC-BY-SA-3.0], via Wikimedia Commons. The sewing machine can’t do a backstitch with a single thread as you might expect, it’s very difficult for a machine to pass the thread though ...