A "Phylum" is a major taxonomic category in biological classification that groups together organisms sharing a fundamental structural framework. It is one of the ranks in the hierarchy of classification, which includes Kingdom, Class, Order, Family, Genus, and Species. For example, the Phylum Chordata includes all animals with a notochord, such as mammals, birds, and fish. Phyla are essential for understanding the diversity of life on Earth. Each phylum encompasses a wide variety of organisms that exhibit similar characteristics and evolutionary traits. For instance, the Phylum Arthropoda includes insects, arachnids, and crustaceans, all of which share jointed limbs and an exoskeleton.