This Useful Notes page deals with planets, both solar and extrasolar, the types of them, their properties and how to avoid Did Not Do the Research when making ones up. (For specific planets orbiting our own star, see The Solar System.) Basically, planets come in three flavors: terrestrial planets, giant planets and dwarf planets. Most astronomers don't consider dwarf planets to be true planets, but they are similar enough to be described here, too.