The largest and most diverse phylum in the animal kingdom is Arthropoda.
Explanation: The phylum Arthropoda includes a vast number of species, such as insects, spiders, crustaceans, and more. This phylum is characterized by having jointed limbs, a segmented body, and an exoskeleton made of chitin. The diversity and adaptability of arthropods have allowed them to inhabit nearly every environment on Earth, from deep oceans to high mountains, making them the most numerous and varied of all animal phyla.