Short answer: Norse mythology organizes the cosmos into nine realms held by the branches and roots of Yggdrasil, the World Tree: Asgard (the Æsir gods), Vanaheim (the Vanir gods), Alfheim (light elves), Midgard (humans), Jotunheim (giants), Svartalfheim (dwarves), Niflheim (primordial ice), Muspelheim (primordial fire) and Helheim (the inglorious dead).
The nine realms, one by one
| Realm | Who lives there | The essential fact |
|---|---|---|
| Asgard | The Æsir: Odin, Thor, Frigg | The gods' fortress, joined to Midgard by the Bifrost |
| Vanaheim | The Vanir: fertility gods | The other divine family; Freyr and Freyja come from here |
| Alfheim | The light elves | Given to Freyr as a gift; almost nothing is told of it |
| Midgard | Humans | "The middle enclosure," encircled by the serpent Jörmungandr |
| Jotunheim | The giants (jötnar) | Chaos at the border; Thor visits often, hammer first |
| Svartalfheim | The dwarves | The forges that produced Mjölnir and Odin's ring |
| Niflheim | Ice, mist and roots | One of the two primordial realms; the spring Hvergelmir boils here |
| Muspelheim | Fire and the giant Surt | The other primordial; its sparks lit the sun and stars |
| Helheim | Those dead of age or sickness | The domain of Hel, daughter of Loki — no glory, but no torment |
The tree that holds it all
Yggdrasil is not a map — it's an organism. An eagle watches from the crown, the dragon Nidhogg gnaws the roots, and a squirrel — Ratatosk — runs up and down carrying insults between them. The nine realms hang from it like fruit, and the gods hold council beneath its branches every day.
Creation began with only two realms: when the fire of Muspelheim touched the ice of Niflheim, the thaw birthed the giant Ymir — and from his dismembered body, the world. The Norse understood the cosmos as the space between cold and fire.
How you travel between realms
The Bifrost, the rainbow bridge, links Asgard to Midgard, and Heimdall guards it without ever sleeping. Every other crossing is a matter of secret paths, rivers, and Odin's eight-legged horse Sleipnir — the only one able to leap into Helheim and return.
What happens to them at Ragnarök
At the end of the world the realms collapse in order: Surt marches out of Muspelheim and burns Asgard, Jörmungandr rises from Midgard's sea, Helheim's dead sail out on a ship made of fingernails, and the Bifrost shatters under the sons of fire. We tell the whole thing in Ragnarök explained.
Quick questions
Are the nine realms planets or physical places?
Neither: they are planes of existence joined by Yggdrasil. The sources never draw them on a coherent map — each poem arranges them its own way.
What's the difference between Helheim and Valhalla?
Valhalla is in Asgard and receives the battle-slain chosen by Odin. Helheim takes those who die of age or illness. It isn't punishment — it's simply the other destination.
Where does the word "Midgard" come from?
From Old Norse Miðgarðr, "the middle enclosure": the human world sits literally at the center of the cosmos, fenced off from the giants by a wall made of Ymir's eyebrows.
The Norse sagas — from the creation to Ragnarök — are told as chaptered audio dramas in MythologyNow.
