FHSST Biology/Biological Nomenclature
Biological Nomenclature & Taxonomy 
Nomenclature simply means to name. In Biology, there is a standard way of naming organisms. This is based on a grouping, or classification, system designed by Carolus (or Carl) Linnaeus. Grouping organisms is called Taxonomy, and the people who do this are called taxonomists.
Taxonomy involves putting all living things into groups based on the characteristics they have in common. These groups, or taxa, can be further divided into smaller and smaller groups, until every single organism is described and named.
For example, dogs and cats are in the same group at one level, because they both eat meat, have fur, 4 legs, and give birth to live young. However, on the next level down they are no longer in the same group, because dogs cannot pull their claws back into their paws, while cats can retract (pull back) their claws. (This is not the only reason they are in different groups, but we don't have the space and time to give all of them.)
Each level of grouping has its own name. In order of decreasing size they are: Kingdom, Phylum (or Division), Class, Order, Family, Genus, Species. (You can remember this order using this poem: King Philip Came Over For Grandma's Soup.)
Using this system, every organism has a binomial (or two part) name, which are always written in italics (or underlined if handwritten). The first part of the name is written with a capital letter and shows which genus the organism is in. The second part is always written with a small letter and shows the species.
How does it work? 
There are 5 Kingdoms - Animals (Animalia), Plants (Plantae), Fungi, Protists (Protista, but now often called Protoctista) and Bacteria (often called Monera). Most taxonomists these days divide the Bacteria Kingdom into two and say there are 6 kingdoms, but in school level Biology we ignore that division and say there are only 5.
Note: A lot of the names used seem to have odd endings or spellings. That's because they come from Latin, which was the main language spoken when Linnaeus started developing this system. A lot of the words we use in Biology have been changed slighly from their original Latin. Instead of saying Kingdom Animalia (for example), which is Latin, non-Biologists will often say Animal Kingdom. You need to practice using both.
e.g. a Lion belongs to the Kingdom Animalia, Phylum Chordata (which means it has a backbone), Class Mammalia, Order Carnivora, Family Felidae, Genus Panthera and species leo. If you simply use Panthera leo, anyone anywhere in the world who has studied Biology will know which organism you are talking about, and why it belongs to that group. This is very useful if you are trying to communicate with someone who doesn't speak your language!