A Primary world is a term used to designate world that can sustain life. They comprise the majority of the worlds in the material plane or about 95%, with the other 5% being doom worlds.
Primary worlds have a tendency to be diverse but in some cases one climate tends to dominate the others. As such, some worlds are essentially desert or oceanic worlds, while others are teeming with forests or are almost entirely covered in frozen wastelands. More than 95% of all worlds have mountains and a forest and an island and a desert. About 50% of worlds have at least one giant lake, frozen wastes, swamps or canyons. A little more than 10% of worlds have a tropical or semi-tropical forest, more than a thousand islands or a super-volcano.