Sorting things is human nature:

The science of Taxonomy, or the classification of living things, is as old as humanity. People have always found it necessary to be able to organize and identify the living things that are a part of their daily lives. Native American legends actually teach us a great deal about the true natural history of the North American continent. In one primitive tribe in the South American rainforest, the classification of medicinal plants and insects was more detailed than that of the modern day biologists who had come to study them with all the tools of 20th century technology! The first person to formalize the classification of living things was Carl von Linnae, also known as Linnaeus (the Latin form), who lived during the 1700's (about 100 years before Darwin). Although his methods were simple and have been expanded upon, some elements of that system are still in use today.

History of Classification:

Linnaeus believed that species were unchanging, and that all life could be organized from most primitive to most advanced along a "Great Chain of Being". The simplest forms of life were placed at the bottom of the chain, while humans resided at the top (males above females), closest to God. We now know that a true classification system is more like a branching bush than a ladder to the heavens. Plants are not inferior to animals, for example, but have simply taken a different strategy towards survival. All organisms alive today are successfully adapted to their respective environments, since they have stood the test of time.

 

How it works:

Linnaeus' method of classification was based on similarities and differences; a logical place to start. He began by dividing all the organisms he knew of into separate Kingdoms based on the greatest similarities and differences. Subdivisions within Kingdoms were called Phyla. Phyla are subdivided into Classes. Classes are subdivided into Orders. Orders are subdivided into Families. Families are subdivided into Genera. Finally, the Genera are subdivided into species. Each species is defined as a group of organisms with the potential to interbreed. Members of different species cannot, by definition, mate and successfully produce fertile offspring. All names are written in Latin, because this is a "dead language" - it never changes and is used only by scientists. The scientific name of an organism is written as "Genus_species". By convention, the genus and species names are either italicized or underlined. Genus name starts with an Uppercase letter while species name starts with a lowercase letter. Sometimes the scientific name has the genus name abbreviated to its first letter. Here are a few examples: