Which category is the largest in biological taxonomy?

In biological taxonomy, the category that encompasses the largest number of organisms is the kingdom. Taxonomy organizes living organisms into hierarchical categories ranging from broad to specific. At the topmost level are the domains, which include Archaea, Bacteria, and Eukarya. Within the domain Eukarya, for example, there are several kingdoms such as Animalia, Plantae, Fungi, and Protista.

The kingdom is a major taxonomic rank that groups together organisms that share fundamental similarities, whether they be morphological, genetic, or ecological. It is broader than other taxonomic categories like phylum, class, or species, which represent increasingly specific groups.

The phylum is a subdivision of the kingdom that groups organisms based on similar characteristics, but it contains a narrower set of organisms. Class is another step down, representing an even smaller grouping, while species is the most specific level, identifying individual organisms capable of interbreeding. Therefore, the kingdom stands as the largest and most inclusive category of life in the traditional domain of biological classification.