The Chordata phylum is the phylum which we are the most physically familiar with, as we ourselves are Chordata. The most distinguishing feature of a Chordata is that it has a bundle of nerves and cartilage supporting these nerves all along the back, also known as the spine.
Chordata also oftentimes have similar bone structures, and even have a few odd structures that are similar, such as slits that connect the throat to the neck, such as in humans where you end up with a rolling pattern, as we do not use these slits as gills.
The classes of the Phylum Chordata are the Amphibia, the Reptilia, the Fish, the Birds, and the Mammalia.