Human beings throughout history, and probably before recorded history, have observed the world about them and have tried to arrange what they see in some form of order. As organisms were observed and described, they were first given names that were descriptive. The names grew in length as new and similar organisms were discovered. In this process, additional descriptors were added to the name of the old form and incorporated into the name of the new form. Synonyms for each organism were about as numerous as the people studying them. The need for change and a plan to change toward was envisioned by the now famous Corolus Linnaeus. Early systems of classification were based upon diverse criteria, and though the binomial system was employed, the grouping of organisms was fairly arbitrary. Since the rise and acceptance of the theory of evolution, efforts have largely been concentrated on a classification reflecting their line of descent. Such a system is called a phylogenetic system, and is considered to represent their natural classification. International organizations now regulate the naming of organisms.
From all of these efforts, a classification system recognizing six major groups called kingdoms has arisen. Within each kingdom there is a hierarchy of subsets, each reflecting closer phylogenetic relationships than shared by members of higher groupings. The ordering of the diversity of the world's organisms is an enormous task that grows as our knowledge grows.