They can be grouped into five basic categories: the Inner Planes (places of raw matter and energy); the Outer Planes (places of gods, souls, and raw philosophy and belief); the Material Planes (worlds balanced between the philosophical forces of the Outer Planes and the physical forces of the Inner Planes, these are the standard worlds of fantasy RPG campaigns); the transitive planes (connecting the other planes and generally containing little, if any, solid matter or native life); and the demiplanes (minor, often artificial planes, often possessing qualities of the other four types of planes).
The planes as a whole are usually presented as a series of concentric circles, with alternating spatial and transitive planes; from the center outwards, they are ordered as follows: Inner, Ethereal, Material, Astral, Outer Planes, and the Far Realm. The Shadow Plane and the Dimension of Time, if they are included, are separate from the others, and usually represented as being connected to the Material Plane. Demiplanes, although most commonly connected to the Ethereal Plane, can be found attached to any plane.
The Astral Plane is the plane of thought, memory, and psychic energy; it is where gods go when they die or are forgotten (or, most likely, both). It is a barren place with only rare bits of solid matter; some creatures, such as the githyanki, use the petrified corpses of dead gods as floating fortresses. The Astral Plane is unique in that it is infinitesimal instead of infinite; there is no space or time here, though both catch up with you when you leave.
The most common feature of the Astral Plane is the silver cords of travelers using an astral projection spell. These cords are the lifelines that keep travelers of the plane from becoming lost, stretching all the way back to the traveler's point of origin.
The immense petrified remains of a dead god. God-isles float on the Astral Plane, where githyanki and others often mine them for minerals and build communities on their stony surfaces. Tu'narath, the capital city of the githyanki, is built on the petrified corpse of a dead god known only as "The One in the Void." God-isles often have unusual effects on those nearby, including causing strange dreams of things that happened to the god when it was alive. God-isles are also the only locations on the Astral Plane that are known to possess gravity or normal time flows.
The Ethereal is often likened to an ocean, but rather than water it is a sea of boundless possibility. It consists of two parts: the Border Ethereal which connects to the Inner and Prime Material planes, and the Deep Ethereal plane which acts as the incubator to many potential demiplanes and other proto-magical realms. From a Border Ethereal plane a traveler can see a misty greyscale version of the plane from which they are traveling; however, each plane is only connected to its own Border Ethereal, which means inter-planar travel necessitates entering the Deep Ethereal and then exiting into the destination plane's own Border Ethereal plane. Many demiplanes, such as that which houses the Ravenloft setting, can be found in the Deep Ethereal plane; most demiplanes are born here, and many fade back into nothingness here[. Unlike the Astral Plane, in which solid objects can exist (though are extremely rare) anything and everything that goes to the Ethereal Plane becomes Ethereal. There is also something here called the Ether Cyclone that connects the Ethereal plane to the Astral Plane.
A small plane connected to mirrors that can be located in any other planes throughout the multiverse. A mirror plane takes the form of a weightless lowly lit space with mirrors floating everywhere. The mirrors reflect your image unless you stare into them and then you can see what they are connected to. The sound of glass often echoes throughout the plane. In some areas vast glass ‘forests’ grow. Mirror planes allow quick travel between the various mirrors that are linked to each. Some say the mirror plane contains a mirror version of any traveler that enters it. This mirror version has an opposite alignment and will seek to slay its real self to take its place. All mirrors connect to the mirror plane.
It is a plane where physical travel can result in time travel. Also known as the "Demiplane of Time". This plane is a fundamental plane for the prime material and many guardians reside here to make sure that the temporal flow of the prime material is not compromised.
Demiplanes are minor planes, most of which are artificial. Demiplanes are commonly created by demigods and extremely powerful wizards and psions. Naturally occurring demiplanes are rare; most such demiplanes are actually fragments of other planes that have somehow split off from their parent plane. Demiplanes are often constructed to resemble the Material Plane, though a few — mostly those created by non-humans — are quite alien. Genesis, a 9th level arcane spell or psionic power, is one of the few printed methods for a player to create a demiplane.
The most notable demiplane is the Demiplane of Dread, the world of Ravenloft.
Portals, conduits and gates are all openings leading from one location to another; some lead to locations in the same plane, others to different planes entirely. Although the three terms are often used interchangeably, there are notable distinctions. Portals are bounded by pre-existing openings (usually doors and arches); the portal is destroyed when the opening is. Portals also require portal keys to open; a key is usually a physical object, but it can also be an action or a state of being. Naturally occurring portals will often appear at random (a common occurrence in the city of Sigil, "City of Doors", some portals only exist for a brief period of time, or shift from one location to another. Conduits are also naturally occurring, but they are natural phenomena, the planar equivalent of whirlpools and tornadoes. Conduits are only known to occur in the Astral and Ethereal Planes. A type of conduit known as a color pool is a common gateway from the Astral Plane to the Outer Planes. A vortex is a link from a Prime Material world to the Inner Planes, which begin in areas of intense concentration of some element (e.g., the heart of a volcano might be a vortex to the Plane of Fire). There also used to be living vortices (plural of vortex) which the sorcerer-monarchs of Athas have managed to maintain, like siphoning water through a hose, and use to empower their "priests," the templars. Gates are portals that are not bounded by physical apertures; gates are rare, and usually appear as a result of magical spells and rare planar phenomena. Lastly, planar bleeding occurs when regions of two planes coexist, such instances can be disastrous for their environs especially if this occurs between the prime material and an outer plane as the energy of the prime material will be easily overwhelmed by the powerful concentration of energy from the outer plane. Anything within the area of the bleeding will be affected by the energy of the outer plane.
Planar pathways are special landscape features appearing in multiple planes or layers of a plane. Travel along a planar pathway results in travel along the planes. Pathways are crucial tactically, because they are very stable compared to portals or gates, and don't require magic spells or portal keys. One notable planar pathway is the River Styx, which flows across the Lower Planes and parts of the Astral Plane. Another is the River Oceanus, which flows through the Upper Planes.
The Feywild (sometimes known as the Plane of Faerie) is a verdant, wild twin of the mortal realm. Towering forests sprawl for a thousand leagues. Perfect amber prairies roll between pristine mountain peaks soaring into the flawless clouds. Emerald, turquoise, and jade green seas crash along endless beaches. The skies are a perfect blue not seen in the mortal world—until storms come, coaldark thunderheads boiling with fierce winds and torrential rains. In this world, arcane power thrums through every tree and rock. All existence is magical.
The creatures native to the Feywild—the enigmatic eladrin, the vicious hags, the wild dryads, and the tyrannical fomorians—are all charged with the mystic energy of this plane. Some are blessed by it, and some are warped. Like the land around them, the fey who inhabit this plane run to extremes. Good fey are noble and just, protectors of the natural world and those mortals they choose to show favor to. Evil fey are dark instinct unleashed, all blood and claw and rage. The creatures of the Feywild can be kind, cruel, noble, monstrous, and savage—often all at the same time.
The Shadowfell is the dark echo of the mortal world, a twilight realm that exists “on the other side” of the world and its earthly denizens. Legend has it that an otherworldly dimness arose around the remnants and tatters of the raw stuff of creation. Over time, these shadows coalesced and assumed a form similar to the natural world, but darker, more ominous, and thrumming with a strange and unexpected power. This murky land spawned beings of its own and drew others from different parts of the cosmos. It came to be filled with a diverse population of creatures, fair and foul.
The Shadowfell is more than just a mirror, even as darkly cast and twisted as it is. This plane is the destination of souls loosed from their bodies. It is the domain of the dead, the final stage of the soul’s journey before moving onto the unknown. For this reason, the Shadowfell draws the attention of any with an interest in death. The power and allure of this place even drew the Raven Queen from the Astral Sea to take residence among the spirits, to govern them, and to monitor their movements as they await the inexorable pull of dissolution.
Arborea is also referred to as "Olympus" or "Arvandor", though technically those names describe separate realms within the plane. Arborea is stylised as a peaceful plane of natural beauty with a multitude of thriving environments. Much of the plane is dominated by vast tall forests, but also includes glades of wildflowers and fields of grain. As a plane that also embodies chaos, it has a wild and often sudden nature. The weather can change drastically at short notice, changing from warm sunshine to raging winds and back again in just a few minutes.
YsgardThe theme of Ysgard is the glory of heroic, individual struggle. According to myth, the twilight of the gods will begin on this plane. Ysgard is also a plane of inspiration and creativity. The Infinite Staircase has its beginning here, and true poetry is said to be found in giants' wells and the mead of the gods. The World Ash, Yggdrasil, has the most connections on this plane.
Ysgard is a place of raw elements, where rivers of earth, ice, and fire crash together in the howling sky, where waves crash in wild oceans. It's the homeland of the heroic bariaurs, the giants and their gods, and the mystical fensir.
Elemental Plane of Fire
Paraelemental Plane of Magma
Quasielemental Plane of Ash & Dust
Elemental Plane of Earth
Quasielemental Plane of Minerals
Quasielemental Plane of Salt
Paraelemental Plane of Ooze
Its people are well known for loving battle. Glorium's nestled on the shore of a great fjord, with its back to the craggy peaks.
Elemental Plane of Water
Paraelemental Plane of Ice
Elemental Plane of Air
Quasielemental Plane of Steam
Quasielemental Plane of Radiance
Paraelemental Plane of Smoke
Quasielemental Plane of Lightning
Positive Energy Plane
Negative Energy Plane
Also know as the Concordant Domain of the Outlands, or Concordant Opposition, is the Outer Plane where the souls of people of Neutral alignment are sent after death. It is popular as a meeting place for treaties between the powers. The Outlands are also home to the gate-towns. At the center of the Outlands is the Spire, atop which Sigil can be seen. The Outlands are the home plane of the neutral-minded rilmani. This plane is also at the center of the Outer Planes and known by its original name Concordant Opposition. Godly powers and Magic/Divine/Psionic powers are lost as one moves toward the center, as well as spells, beginning with the highest levels of spells at the farthest out and then gradually losing the lower ones step by step the further one moves inward. Within 100 miles (160 km) of the center, not even chemical reactions take place, and neither man nor deity can get closer than 100 miles (160 km). The Mediators of Nirvana (Mechanus), was originally intended for Neutral Powers (deities) and created by the Powers (deities) of creation, but each Neutral Deity asserted their individual influence causing it to become unbalanced, then were cast out by the powers of creation. It also states that three lights of balance exist at the center of this plane, one for each Mediator in Nirvana (Mechanus).
The closer to the Spire, the harder it is to use magic-related powers. However, most of the towns, portals, realms, etc. are located far enough not to suffer from these impediments. At 500 miles (800 km) from the Spire, illusions no longer work. At the very base of the Spire, absolutely all magic is neutralized.
Notice Rilmani seem unaffected by such limitation, except maybe in the first ring.
The Outlands is the location of a number of godly realms, including the following:
The Celtic gods (Daghdha, Diancecht, Goibhniu, Lugh, Manannan mac Lir, Oghma, and Silvanus) share the realm of Tír na nÓg on the Outlands.
Gate-towns are settlements which are built around a permanent portal to a certain Outer Plane on the Great Wheel. Gate-towns are important strategically because they provide a (relatively) stable way to enter a desired Outer Plane. The gate-towns reflect the plane that they lead to. There are 16 such gate towns, each connected to their own Outer Plane:
Madness is the best way to describe Xaos, the gate-town to Limbo. There's so much chaotic energy here that the town shifts and changes in an eyeblink. The folks here can handle it - lots of travellers can't.
Bedlam's the gate-town to Pandemonium, and it's a crazy place that doesn't look quite right when wandering about the streets. Don't assume anyone here's completely sane, but don't think they're all deranged either.
A diseased realm of squalor and verminous fecundity, choked with razorvine and bizarre alien parasites. People here are so desperate that they have taken to the worship of the Lady of Pain en masse, constructing their makeshift mud hovels with blades atop them in the hopes of placating her. They pass their days agonizingly trying to numb their pain beneath layers of hard vices, slowly mutating into forms less and less recognizable. Elsewhere in the city, in massive cruel fortresses, the rich and powerful parade inhuman wealth and power before the suffering masses.
City of Traitors and Betrayers. The inhabitants constantly plot against one another, attempting to send others to the vast prison below the city before others arrange to have them sent there. It is arranged in concentric circles, the innermost housing the rich and powerful. The city gate to Carceri is a pair of crossed arches covered in moaning skulls of the betrayed, and is activated by a chain link.
A bleak, gray city where colors are forbidden, built like a maelstrom that spirals to a central murky tarpit—a sinkhole to its patron realm. Ruled by a once human wizard garbed in chains and an iron wolf mask who is in turn served by a cadre of beholders. Its gate is a massive blood red screaming face.
An ever-changing furnace of cracked lava rock descending into steaming runlets of lava covered with hundreds of iron towers, hot as frying pans, that stretch up to a roiling sky choked with black smoke. The creatures that live there, mostly fire elementals, yugoloths, barghests as well as a subrace of nomadic humans called Desh, do so in order to savor the endless pain and suffering that comes from living there.
A massive fortress-city enclosing a military camp endlessly engaged in preparations for war. Blacksmiths bang away at hot metal in the streets while corner venders sell military provisions and war animals. The city is built on a hill and is surrounded by a series of seven circular walls, each rising higher than the last. At the center, in a section of the city known as the Crown, a winding stair penetrates deep underground to a grey-green nimbus of twisting light like a great cat's eye: the portal to the city's patron plane.
The gate-town of Automata leads to Mechanus. It's full of lawful, orderly, overly organized denizens who can't strap on their own boots without filling out a form. In short, watch out for the red tape. But it's the only place outside of Mechanus that one can find the strange new clockwork weapons that've been developed on the plane of law. Crossbows that fire more than one bolt, armor with built-in dart-throwers, and even stranger things can be found here, as long as the buyer's extra-generous with the platinum (and is willing to fil out the proper forms).
Fortitude is the gate-town to Arcadia, although some planewalkers call it the Egg because the town's wall makes a perfect oval shape. The town a beautiful place, but it's an ordered beauty. The trees line the parks in neat rows, the grass is uniformly clipped, and the streets are polished to a shine.
In Mount Celestia's gate-town, Excelsior, the streets are paved with gold-flecked brick and floating castles of paladin lords keep the perimeter safe.
The center of Outlands commerce.
Ecstasy holds the gate to Elysium. The town's known as the City of Plinths for the tall stone and iron monuments that dot the burg. The denizins sit idly and contemplate the multiverse. Everyone else in town is equally motivated - they do what they want, when they want, and generally enjoy life. This isn't a bad place for a planewalker to take a break, but don't look for much from the local folk - they're busy with their own cares.
Although it looks like a ruin, Faunel is actually the gate-town to the Beastlands. This town has been overgrown by plants and is populated by more beasts than people. This is a wild place overtaken by nature. A powerful protector guards the area maintaing the natural order.
Sylvania is the gate-town to Arborea. The site is often described as a big party, and seems to twist and turn to no end; the buildings are more works of art than practical structures. Prominent locations include the Sensate embassy and the temples to the Greek powers and the Seldarine. The "portal" to Arborea is simply getting oneself lost in the local woods. Once you're thoroughly lost, Arborea finds you. On the other side of the portal is Thrassos. Sylvania is ruled by a group of possessor entities known as the Seven Spiritors.