Nomenclature codes or codes of nomenclature are the various rulebooks that govern biological taxonomic nomenclature, each in their own broad field of organisms. To an end-user who only deals with names of species, with some awareness that species are assignable to families, it may not be noticeable that there is more than one code, but beyond this basic level these are rather different in the way they work.

The successful introduction of two-part names for species by Linnaeus was the start for an ever-expanding system of nomenclature. With all naturalists worldwide adopting this approach to thinking up names, there arose several schools of thought about the details. It became ever more apparent that a detailed body of rules was necessary to govern scientific names. From the mid-19th century onwards, there were several initiatives to arrive at worldwide-accepted sets of rules. Presently nomenclature codes govern the naming of:

• Algae, Fungi and Plants – International Code of Nomenclature for algae, fungi, and plants (ICN), which in July 2011 replaced the International Code of Botanical Nomenclature (ICBN) and the earlier International Rules of Botanical Nomenclature.
• Animals – International Code of Zoological Nomenclature (ICZN)
• Bacteria and Archaea – International Code of Nomenclature of Prokaryotes (ICNP), which in 2008 replaced the International Code of Nomenclature of Bacteria (ICNB)
• Bacteria and Archaea described from sequence data – Code of Nomenclature of Prokaryotes Described from Sequence Data (SeqCode)
• Cultivated plants – International Code of Nomenclature for Cultivated Plants (ICNCP)
• Plant associations – International Code of Phytosociological Nomenclature (ICPN)
• Viruses – The International Code of Virus Classification and Nomenclature (ICVCN); see also virus classification