> In biological classification, what's the largest and most inclusive rank forliving things?And the answer: Domain. In taxonomy, there are three domains – Archaea, Bacteria, and Eukarya – and thefirst two involve microorganisms. The third, Eukarya, involves most plants andanimals. These organisms are sorted into seven more categories: Kingdom, Phylum,Class, Order, Family, Genus, and Species.Taxonomy, or the science of classifying living things, tells the story of alllife on Earth. Sometimes called the Phylogenetic Tree, taxonomy illustrates therelationships between living things. There are currently around 2 million known species on Earth. However, that is byno means a complete list: scientists discover new species nearly every day. Thismeans that every new discovery adds to ever-enlarging categories ofclassification – some of which eventually require reordering. Shortcomings aside, taxonomy has been the dominant biological classificationprocess for around 250 years. Its founder, botanist Carl Linneaus, invented themethodology in the 1700s when he realized the botanical nomenclature of 18thcentury Europe was highly confusing and inefficient. The method he eventuallyestablished was based on morphology, or the study of physical form andstructure. This was revolutionary for a study that had been operating off ofclassification using analogous traits: structures in animals that appearsimilar, but actually come from very different origins. Under this form ofclassification, birds would be more closely related to butterflies thanreptiles, based on the power of flight. To learn more about the history and practice of taxonomy, check out the videobelow.