Today all living organisms are classified. Carolus Linnaeus developed the classification system in 1735. The classification system is based on a hierarchy, or a system of ranks. All organisms are grouped based on biological meaning. Organisms that have similar biological mean are grouped into taxa. Think of taxa as all baseball players. Hockey players would not belong in this taxa because they don't play baseball instead they play hockey, so all hockey players would form their own taxa. As Linnaeus' classification system becomes more specific, that smaller the taxa become. Linnaeus' classification system includes seven hierarchical taxa: 

  • Kingdom(most inclusive)
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species(most specific) 

In this article we will follow the classification of humans as an example.



Kingdom is the most inclusive of all of Linnaeus' classification categories. Many phylums make up a kingdom. When Linnaeus developed his system he only included two kingdoms: animals and plants, but today scientists believe there are at least 5 kingdoms: animals, plants, fungi, protists, and bacteria. Humans belong to the kingdom Animalia, where all multicellular organisms are placed.


A phylum includes organisms that are different but share major characteristics such as a spinal cord. Many classes make up a phylum. Humans belong to the phylum Chordata. The phylum Chordata includes all vertebrates (organisms that have a spinal cord).


A class is a bit more specific than a phylum. Many orders make up a class. Humans belong to the class Mammalia, which includes all organisms that have warm blood, hair, and produce milk for their young.


Families make up an order. An order is not as inclusive as a class. Humans belong to the order Primates, which includes all organisms that have fingernails, a relatively small number of teeth, and color vision.


Many genera (singular: genus) made up a family. A family is the third most specific taxa of all living things. Humans belong to the family Hominidae. All the organisms in the family Hominidae include humans and relatives of humans closer than chimpanzees.


Many species make up a genus. The genus is the second most exclusive taxa in Linnaeus' classification system. Humans belong to the genus Homo. All the organisms in the genus Homo are either human or great apes. 


Species are a group of organisms that are able to mate and produce fertile offspring. Species are the most exclusive taxa in Linnaeus' classification system. Humans belong to the species Sapiens. 

A good way to remember Linnaeus' classification system is to use an acronym. A common acronym is Keep Pond Clean Or Frogs Get Sick. This acronym is good but I urge you to make up your own. When you make up your own acronym, it is easier to remember because it will relate to you.

 Binomial Nomenclature

When scientists refer to a specific organism they use a two-part name. Binomial nomenclature is the name of the two-part scientific naming system. The two-part name gives some information about the organism. Most scientific names are in Latin or Greek because binomial nomenclature was developed in the 18th century, when Latin was the language of science.  Carolus Linnaeus devised binomial nomenclature. Here is a common scientific name you should recognize Homo sapiens. The first word, Homo, is always capitalized. It indicates the Genus name of the organism. The second word, sapiens, is the name of the species. It is never capitalized. So the next time you want to plant a tree in your garden or impress someone, and you see a scientific name, you will know what it relates too. 



Carl Linnaeus: Father of Classification (Great Minds of Science)
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