For a true planar, the planes means the Outer planes, the Great Ring. No other place has the same richness or the same tingle of power as any of the Outer Planes. They comprise the greatest of all the rings, each plane its own universe. Some have limits, others are infinite. Each plane is linked to those adjacent to it by fixed gates - folks call the path between them the Great Road. With a map to the gates, a body can travel the entire circumference of the Outer Planes. 'Course, that's provided the fiends don't get him first...
Where the prime-material worlds vary by natural, technical, and magical development, and the Elemental planes contrast by substance, the Outer Planes differ by morality. Each one is attuned to a particular alignment, and the berks and terrain within it subtly or overtly reflect that alignment. The powers choose their homes within the planes of their own alignments, too. Limbo is chaotic and ever-changing, Mechanus is rigid and organized, Mount Celestia is peaceful, and the Abyss is brutal and deadly.
Primes have different names for the planes, which comes from their own peculiar understanding of the multiverse - like the Twin Paradises, the Nine Hells, the Seven Heavens, Tarterus, Olympus, Asgard, Hades, and Nirvana. Don't be thrown by them. Also, try not to laugh at the sods when they use these tags; it's almost certain they would've gotten the names right if they'd bothered to ask folks who know better.
While it seems that the seventeen Outer Planes have little in common, that's only because most planars take for granted what they do have in common. First, a cutter can walk and breathe on most of the Outer Planes without spells, magical devices, or other pretections - that's a big change from the Inner Planes. Second, most all places have a clear up and down: Down's the earth under a basher's feet and up's the sky overhead. Third, most planes got a north and south. It ain't the same from plane to plane, or even from layer to layer' but it's still useful for getting around.
A prime shouldn't kid himself, though - the Outer Planes are different from any weak prime-material imitation. Compared to the Prime, everything's greater here. Mountains are loftier, glaciers colder, deserts hotter, and even the colours have an extra hue. Nothing on any prime-material world can ever quite match its counterpart on the Outer Planes. After all, what's a basher supposed to expect in the homes of the gods?
Another important thing that many of the Clueless don't realize is that a plane's not just a single place. It's got divisions and areas within it, and things can change from area to area. Planes are made up of layers, different worlds that all fall within the plane. Generally, each layer falls under the sway of a different power or group of powers, which accounts for often start differences in appearance.
In some places, like the Abyss, the layers stack up like a messy deck of cards, mostly on top of each other, with an occasional layer that sticks out where it shouldn't. On Baator, the nine layers form the tiers of a descending cone, perfectly regular to each other. Other layers are joined by rivers, bridges, or - most fantastic of all - great clockwork gears.
Within a plane, or even within a layer, there can be a lot of different realms. A realm is an area ruled by a power or group of powers, who fashion the land to suit their desires. Each realm can modify the physical laws of the land. Gravity, weather, and even directions are subject to the control of the local powers. Hence, it's usually easy for a cutter to tell when he's entered a new realm There's a shift in the landscape, one that matches the ideals of the new rulers, that's noticeable to all but the most addle-coved travellers.
The Outer Planes are divided into three main groups: Upper Planes of Good, the Lower Planes of Evil, and the Boundary Planes of Neutrality. Here's a good piece of advice: The Lower Planes are the site of the ever-raging Blood War, the lawless conflict that's raged for eternity between the tanar'ri and the baatezu. They're not places the foolish can pass through and live.
Special Note: The Outer Planes do not touch the Inner Planes or the Prime Material, as shown on the map of the Multiverse.
The Outer Planes
|Mount Celestia||Bytopia||Elysium||The Beastlands||Arborea|
|Baator||Gehenna||The Gray Waste||Carceri||The Abyss|