This chapter details the characteristics of the phylum Chordata. Unlike its subphylum Vertebrata, Chordata features the subphyla Cephalochordata and Urochordata as two subphylums whose members exist without backbones. Modern phylogenomic research shows that Urochordata is the sister group to Vertebrata, a clade known as Olfactores. Like all chordates, cephalochordates possess a notochord, dorsal hollow nerve cord, pharyngeal gill slits, postanal tail, and true coelom. The chapter also showcases some illustrations to feature the parts of Cephalochordata and Urochordata members. It mentions that future research should consider looking into the evolutionary-developmental pathways of urochordates or using tunicates to better understand the derivation of vertebrate neural development.