What is a Planet?

Updated 9/16/2006 to mesh closer with IAU's official plant definition.

The original meaning of the word Planet is "Wanderer" or "Wandering Star" which was a good description of how planets looked as they moved across the stars from night to night in anchient times.

However with the discovery of many objects similar in size to Pluto, and one larger in our own solar system, the IAU (International Astronomers Union) has layed down what a planet is after some years of debate.

They define two classes of Planet, where a mainstream planet is round (due to gravity), orbits a star, and has cleared its orbit of other bodies, and a dwaf plant is defined as being round, orbits a star, but has not cleared it's orbit of other objects. This places Pluto, Ceres, and UB313 (Xena) into the Dwarf Planet catagory.

However the IAU definition on partialy fits the bill when cataloging plaents according to logical types.

Considering that were discoving planets around other stars, numbering close to 200 in count now, there needs to be a more consise definition and classification system.

Within the classification of Planet, will also use some Subclasses which best fit what type of Planet it is. Hopefully the IAU will come up with a more concise classification scheme in the coming years that can be used.
Class Definition
Belt (B) Belt Planets(worlds) are planets like Pluto, Sedna, Ceres and Eris (Formerly UB313 aka Xena) which are planets originating in a belt or cloud of similar objects. Pluto, UB313, and Sedna all appear to originate from the Kuiper Belt, leading to this logical classification. Any size planet may be placed in this class if it's part of a belt like system.  This Catagory matches the "Dwarf Planet" definition of IAU, but allows for any size of planet to be part of a belt system.
Dwarf (D) Dwarf Planets(worlds) are smaller body's, less then half the earths mass, that have enough gravity that they compact themselves into a roundish shape (or Hydrostatic Equalibrium). 
Stock (S) 
 Stock Planets(worlds) are planets that are Earth like (Stock meaning normal) with masses from 1/2 the Earth up to 5 Earth masses.
Huge (H) Huge Planets are worlds that are from 5 times the mass of Earth up to 8 earth masses (Neptune sized) that are not Gas Giants (or mostly there mass is from rock and not gases)
Giant (G) Giant Planets are Neptune sized, 8 masses earth and up, but not including Gas Giants that are massive enough to have some fusion in thier cores (Brown Dwarfs), which is though to be about 13 Jupiter Masses.
Double or Multiple(M)

Double (or Multiple) Planet class is used to describe a two or more planet system, where at least two objects orbit each other around thier Bary Center and both are at least dwarf planets. The Pluto-Charon system would be a good example of this Class. Any size planet may be placed in this class if it's part of a multiple system.

A descriptive word may be used in front of the class, that helps to describe the type of planet it is. Such as Cold Dwarf Planet Mars, Ice Belt Planet Pluto, Habitable S-Planet Earth, etc...