Here's how the hierarchical classification system works:

* Domain: The broadest category (e.g., Bacteria, Archaea, Eukarya)

* Kingdom: A large group of organisms sharing general characteristics (e.g., Animalia, Plantae, Fungi)

* Phylum: A group of related classes within a kingdom (e.g., Chordata, Arthropoda, Mollusca)

* Class: A group of related orders within a phylum (e.g., Mammalia, Aves, Reptilia)

* Order: A group of related families within a class (e.g., Primates, Carnivora, Rodentia)

* Family: A group of related genera within an order (e.g., Hominidae, Felidae, Canidae)

* Genus: A group of closely related species (e.g., Homo, Panthera, Canis)

* Species: A group of organisms that can reproduce with each other and produce fertile offspring (e.g., Homo sapiens, Panthera leo, Canis lupus)

So, "phylum" is a level of classification within a kingdom.