In the mid-18th century, Swedish biologist Carolus Linnaeus wrote Systema Naturae- a land mark book because of the way Linnaeus named and organized the plants and animals known at that time. First, he employed a system called the “binomial system of Nomenclature” using Latin which was the one language shared by all educated people of Europe at the time. The first term denotes the genus, a grouping of very similar organism to which organism belongs (plural form: genera)
The second term denotes the organism specie- a specific group of closely related organism within a genus. The full species binomial (two part) name always includes genus and species. For example, the modern domesticated horse is named Equus caballus, while its close relative, one of the zebras, is Equus burcelli.
Today, groupings do not stop at genus and species, but include broader taxonomic group, arrangement of organisms into hierarchical classification from species, genus, family, order, class, subphylum, Phylum and kind of Classification.
There are two kinds of classification. These are the artificial system and the natural system. Classification is artificial if classes of organism are set up arbitrary. Pliny the elder 923-79 A.D) used the form criteria and size for the plants classification into herbs, shrubs and trees. But during the Middle Ages, plants were classified based on their uses, such as medicinal, edible or poisonous plants.