What is a kingdom?

Kingdom refers to a specific group of organisms that are defined by a certain hierarchy of classifications. During the 18th century, initial classification of organisms was made by Linnaeus, who at that time divided living things into two groups; plants and animals. As biological sciences progressed and more organisms were discovered, the two-kingdom system was insufficient to classify the new findings.

Currently, six kingdoms consist of animals, plants, bacteria, fungi, protists and archea. These classifications are made based on an organissm's cell type, number and how their cells function. After the specific type of kingdom, the six kingdoms are further divided into phylum, class, order, family, genus and species, in that order. Click on the url link below to learn more about the classification.