To facilitate the study of kinds and diversity of organisms, biologists have evolved certain rules and principles for identification, nomenclature and classification of organisms. The branch of biology dealing with these aspects is Taxonomy.
In classification, the organisms which closely resemble one another are placed together in a group. The groups which have similarities with each other are combined to form larger groups. Thus, animal or plant group having natural relations is known as Taxonomic category.
There are seven major categories. The Kingdom is the higher category of taxonomic studies. Other major categories in descending order include phylum, class, order, family, genus and species.
Largest unit of classification is Kingdom.
Kingdom:
Kingdom is the highest category in biological classification.
It is a group of phyla or divisions with certain common characteristics.
Presently there are five kingdoms: Animalia, Plantae, Fungi, Protista and Monera.