If you look at my body under a magnifying glass, you will see a lot of little rings across my entire body . . . looks kind of like corduroy or a lot of rings connected together. These rings are called segments. When I am all grown up, I will have 120-170 segments. On the first segment is my mouth and on the last segment is my anussort of like the beginning and the end.
If you had a microscope and looked really, really closely at each segment, you will see something that looks like a bunch of small hairs or bristles. (And I'll bet you thought worms were bald.) These bristles are called setae (pronounced see-tee) and they help me move. I have four pairs of these bristly "hairs" on each ring or segment.