A Chordate is an animal belonging to the phylum Chordata, characterized by having a notochord, a dorsal nerve cord, pharyngeal slits, and a post-anal tail at some stage of their development. This group includes a wide variety of animals, such as mammals, birds, reptiles, amphibians, and fish. Chordates can be divided into three main subphyla: Cephalochordata (lancelets), Urochordata (tunicates), and Vertebrata (vertebrates). The vertebrates are the most complex and include species like humans, dogs, and whales. Chordates play essential roles in ecosystems and exhibit diverse forms and behaviors.