Britannica AI Icon

Quick Summary

In biological classification, a kingdom is a major taxonomic category that ranks above the phylum and below the domain. Historically, organisms were divided into two kingdoms: plants and animals. However, the discovery of microscopic life, which often exhibited characteristics of both, led to the proposal of additional kingdoms, such as Protista.123

Current systems often recognize divisions based on cell structure, distinguishing between prokaryotes (like bacteria) and eukaryotes. This has led to various classification schemes, including a five-kingdom system (Monera, Protista, Fungi, Plantae, and Animalia) and a three-domain system (Bacteria, Archaea, and Eukarya). A taxon is any unit used in biological classification, with kingdom being one of the highest ranks.245

Summary created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Ask Britannica AI about this topic

Britannica doesn't have a full article on this topic, so we've curated a list of our relevant coverage.