In biological classification, a "phyla" (plural of phylum) is a major taxonomic rank that groups together organisms sharing a common body plan and structural features. Phyla are one of the primary categories used to organize life on Earth, sitting above classes and below kingdoms in the hierarchy of classification. For example, the Chordata phylum includes all animals with a backbone, such as mammals, birds, and fish. Each phylum can contain multiple classes, which further divide organisms into more specific groups. The diversity within a phylum can be vast, encompassing various species that may look and behave very differently. For instance, the Arthropoda phylum includes insects, arachnids, and crustaceans, all of which share a segmented body and exoskeleton.