Worms are invertebrates, which means they do not have a backbone. They belong to different phyla, including Nematoda, Annelida, and Platyhelminthes. The term "worm" is used to refer to various animals with a long, thin body that moves without legs. The word "worm" is also used in everyday language to describe other living forms such as larvae, insects, millipedes, centipedes, shipworms, or even some vertebrates. In summary, worms are classified as invertebrates, and they belong to different phyla depending on their characteristics.