Classifying Organisms into Groups

Organisms can be classified into specific groups based on their shared characteristics and according to the principles of biological classification.
The main groups, from largest to smallest, are Kingdom, Phylum, Class, Order, Family, Genus, and Species. This is also remembered by the acronym KPCOFGS.
The scientific name of an organism is made up of its Genus and species name, written in italics (or underlined if hand-written). The Genus name is capitalised, but the species name is not.
The classification system itself is hierarchical, meaning each level includes the one below it. For example, all species within a genus share certain traits. All genera within a family share even more traits.
The main five kingdoms that organisms are classified into are Animalia, Plantae, Fungi, Protista and Monera. Classification within these kingdoms is based on factors such as cell structure, mode of reproduction and nutrition.
There are three fundamental domains of life: Bacteria, Archaea, and Eukarya. The domains Bacteria and Archaea consist of prokaryotic microorganisms while the Eukarya domain includes all organisms with eukaryotic cells.
Classifying organisms can help scientists to see links between different species. For example, species placed in the same group are more closely related than species in different groups.
The classification system is continually updated as new genetic and fossil evidence is discovered. This evidence can change our understanding of evolutionary relationships. For instance, we now understand birds are closely related to certain groups of dinosaurs.
The identification and classification of species is critical to conservation. By understanding the relationships between different organisms, we can make informed decisions about how best to protect them.
Be aware that the accentuation of certain characteristics - such as similarities over differences - may affect classification. This is known as bias in taxonomy and is a point of ongoing debate in biology.