The document summarizes the key characteristics of the phylum Chordata. Chordates are defined as having a notochord, hollow nerve cord that forms the spinal cord, pharyngeal pouches that develop into structures like gills and ears, and a postanal tail. The phylum contains invertebrate chordates like tunicates and lancelets, as well as the subphylum Vertebrata which includes fish, amphibians, reptiles, birds, and mammals.