It consists of many steps and each step is mentioned as a rank or category. Each category is a unit of classification. Various levels in taxonomic hierarchy are:
Species —> Genus —> Family —> Order —> Class —» Phylum —> Kingdom.
(a) Similar individuals form a group called species. All the related species form the next rank genus, e.g., Rana tigrina (Frog), Ram is genus and tigrina is species.
(b) Related genera are kept in a family e.g., Petunia, Solanum and Datura are the members of family Solanaceae. The related families comprises Order e.g., Solanaceae and Convulaceae comes in order Polynomials.
© All orders make classes, e.g., bony fishes and cartilaginous fishes are included in class Pisces.
(d) Various classes like amphibia, aves, mamamalia form a Phylum (Chordata), and all Phylum comes in kingdom Animalia.