Chordata is a diverse phylum of animals characterized by the presence of a notochord, a dorsal nerve cord, pharyngeal slits, an endostyle, and a post-anal tail at some stage of their development. This phylum includes well-known subgroups like vertebrates, which encompass mammals, birds, reptiles, amphibians, and fish, as well as some invertebrates like tunicates and cephalochordates.