The modern system of classification (Binomial nomenclature) accepted by biologists today was proposed in 1758 by the Swedish botanist Linnaeus (1707-1778) in his 'Systema Natura'. This system was based on morphology. Linnaeus proposed that each type of organism should be given a unique Latin binomial (consisting of two terms) to set it apart from every other type of organism. The first word in this binomial designates the genus to which the species belongs.
A genus (plural: genera) contains one or more closely related and similar species. The second word in the binomial denotes the species itself, For example, according to this system, the domestic cat is Fe is domestica. This indicates that the domestic cat has been placed in the genus Felis and within that genus, has been given the specific or species epithet domestica. This complete name distinguishes the domestic cat from other species in the genus Felis, such as Felis bengalensis (leopard cat) and Felis chaus (jungle cat).
It also means that all species coming under the genus Feliis are more closely related and similar to one another than to species coming under any other genus. The generic name always begins with a capital. The specific name on the other hand begins always with a small letter. Both 'the generic and the specific names are italicised in print or are underlined in manuscript or typescript.