Taxonomy is the identification, naming, and classification of organisms. The taxonomic hierarchy for classifying birds is:
Kingdom: Animalia - all animals on earth
Phylum: Chordata - animals on earth which have a spinal chord
Subphylum: Vertebrata - animals which have a true backbone
Class: Aves - all living and extinct birds
Birds are a group of warm-blooded vertebrates characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweight skeleton.
Taxonomy data compiled from The eBird Taxonomy using birds with a category of "species".