The science of classification is called taxonomy. A taxon (plural taxa) is a group of organisms classified together because they are more closely related to each other than to any other organism. If such a taxon is made up of an ancestor together with all of its descendants, it is called a clade. Clades are used for reconstructing evolutionary relationships and the results are displayed into a cladogram or evolutionary tree. The following ranks of taxonomic groups, each more inclusive than the one below it, are used when classifying an organism:
Kingdom
Phylum
Class
Order
Family
Genus
Species