Taxonomy is the science (or some would say art) of classification. It comes from the Greek words 'taxis' and 'nomos' meaning respectively arrangement and law. One of the most famous taxonomies is that devised by the Swedish scientist, Carl Linnaeus.
Even though the word taxonomy is derived from the Greek the actual labelled divisions that identify one particular species are in Latin e.g. Pipistrellus pipistrellus, which is the Common Pipistrelle bat. As you will notice the name is italicised with the first half (the genus) having a capital letter whereas the second part of the name (the trivium) always begins with a lowercase letter. The following table shows the taxonomic description of the Common Pipistrelle.