Why is binomial nomenclature used in taxonomy?

Answer 1

The reason is that Carl Linnaeus set up a classification hierarchy: Kingdom, Class, Order, Genus and Species, but he thought that above Genus the ranks were merely conveniences. Genus and species were, however, the "works of God" and therefore natural, so he gave a name to the Genus (such as Homo for humans) and a name to the species in that genus (for him our species in the genus Homo was sapiens, but he had other species, including "troglodytes", which may have been a chimp). So the "binomial names" became the fixed names of species thereafter.

In the early nineteenth century, it was decided that any species name that was in the tenth edition of Linnaeus's Systema naturae would be used afterwards, except for the other Homo species, which had by then become Pan troglodytes and Gorilla gorilla.