Biological Classification
The scientific classification of life, otherwise known as 'biological classification', is the method used by biologists to group organisms together by type. The different levels are called taxa. The different taxa are: Kingdom, Phylum, Class, Order, Family, Genus, Species.
Kingdom is the broadest of the taxa. All animals are in Kingdom Animalia. All plants are in Kingdom Plantae. Linnaeus attempted to name organisms in a way that would make sense to all scientists. For example, the group “Mammalia” was named for the mammary glands with which they nurse their young. Linnaeus' system recognized two 'Kingdoms' - Vegetabilia and Animalia. Today, most biologists utilize a six Kingdom system, as follows: Animalia, Plantae, Fungi, Chromista, Protozoa, Bacteria.
Domain, a level above Kingdom, has become popular in recent years. A three-domain system was first proposed in 1990, but has not yet been generally accepted amongst biologists.
Source: http://www.bellaonline.com/articles/art70331.asp
