Taxonomy is the science of naming and classifying organisms on the basis of their evolutionary relationships.  With well over a million described animals, there must be a consistent and organized system for cataloging all of these species in a manner that correctly reflects their evolutionary relationships.  Such a system was first proposed by Carlolus Linnaeus (a Swedish botanist) in his Systema Naturae published in 1756. It requires that each organism be given a unique, Latin (the universal language of those times) binomial, which is called a species.   For example Homo sapiens is the binomial for humans. Remember, a species is a binomial, which means that it is not one word - the genus is Homo, the species is Homo sapiens  (i.e., the species epithet is never used alone)! Note that because the binomial is written in a foreign language it must be placed in italics or underlined!  Also note that the genus is a noun and Capitalized, while the species epithet (i.e. sapiens) is usually a descriptive adjective.  Sometimes, however,  it is a name that honors a biologist.  For example, Rana blairi (the plains leopard frog) was named in honor of the famous amphibian biologist W.F. Blair.