In biology, binomial nomenclature is a standard convention used for naming species. As the word 'binomial' suggests, the scientific name of each organism is actually the combination of two names: the genus and the species (as epithet). The genus is typically capitalized, while the species is not; both are typeset in italics. For example: Homo sapiens. Often the genus will be abbreviated; an example is E. coli.
The value of this system is chiefly that, although a given species may be named differently in different languages, the scientific name will always be the same. Ideally, scientists can meaningfully and unambiguously refer to a species when describing their work to other scientists. Nomenclature intends to keep names stable, but quite often this is not true: an organism may have several names, reflecting different rank and position in taxonomy, depending on opinion (see synonymy), conservation according to nomenclature codes, and new findings based on molecular phylogeny. Nomenclature must acknowledge the achievement of scientists who were first to name a taxon.
The genus and species name are, of course, only part of the larger classification of the organism:
Carolus Linnaeus invented this classification, but it is a common misconception that he also invented binomial nomenclature; in fact it dates back to the Bauhins. Linnaeus only was the first to popularize it, and it is only one aspect of his systematical achievements or misachievements (such as oversimplifying fungal systematics).
Binomial nomenclature is only one of many conventions used to name organisms. Nomenclature codes rule the naming of plants (incl. Fungi, cyanobacteria) / cultivated plants / animals / bacteria / viruses. These codes differ. For example, the ICBN plant nomenclature does not allow tautonymy, whereas the ICZN animal code allows it. A BioCode has been suggested to replace several codes, but there also is debate of a PhyloCode to name clades of phylogenetic trees.
For more information on this system, please see scientific classification and numerical taxonomy.