The Yggdrasil is the ‘World Tree’ of Norse mytholgy. Of course that answer is far to simple and there is much of myth and legend about this tree.

The Yggdrasil’s name is thought to derive from the old norse ‘Yggdrasill’, meaning Odins’ (Ygg’s) Horse. It is a great Ash tree which is said to hold all the worlds of Norse mythology.

The tree has three roots which lead to different realms.

Asgard, the realm of the Aesir, the race of Norse gods. The legend of the building of Asgard is supplied in a link at the end of this article.

Jotunheim, the realm of the frost and rock giants.

Niflheim, the death realm, Helheim is located within this region.

The tree also sits over three wells. The Well of Wisdom (Mimisbrunnr), The Well of Fate (Urdarbrunnr) and Hvergelmir, the source of many rivers.

Four deer run about the branches of the tree and represent the four winds. They are named Dainn, Dvalinn, Duneyrr and Durapror.

A wise eagle also sits in the branches of the tree and a squirrel named Ratatoskr runs gossip-laden messages between the eagle and the wyrm (/dragon or snake), Niohoggr who is said to gnaw at the root over Niflheim.

There are also tales of a tree snake, Vidofnir, a goat that eats the leaves and a golden cock that sits on the topmost bough of the tree. Many more snakes are said to gnaw at the roots of the tree.

The tree is a holy place and where the Aesir are said to hold their courts.It is also central to the Norse legend of Ragnarok, the End of the World. Ragnarok tells of the final battle between the Aesir, lead by Odin and the fire giants and monsters led by Loki. It states that almost everything will be wiped away during this battle, including the gods themselves and going so far as to say that the universe will be torn apart by this ‘apocalypse’.

Every part of this battle was well described in Norse literature and known to all through poems and sagas such as the Poetic and Prose Eddas (The Elder and Younger). Yggdrasil is said to save and protect the only survivors, Lif and Lifthrasir, who feed on Yggdrasil’s dew and are sheltered by its branches.

There are several literary mentions of Yggdrasil, either by name or by inference and the links to four of them are given here. Voluspa, Hovamol, Grimnismal and Prose Edda

The Yggdrasil tree has become known in a variety of media including books and video games. Such instances can be find in the final link below.

Sources

http://www.pantheon.org/articles/a/asgard.html

http://www.pantheon.org/articles/j/jotunheim.html

http://en.wikipedia.org/wiki/Yggdrasil#cite_note-DRONKE7-1

http://www.fact-archive.com/encyclopedia/Yggdrasil