Yggdrasil
Yggdrasil (also Mímameiðr or Lérað) is the world tree of Scandinavian mythology, whose trunk, branches and roots reach all levels of the world. Yggdrasil is a giant ash that supports the entire universe.
There are three wells or springs at the foot of Yggdrasill: Urdarbrunnr, the well of fate, Hvergelmir, or the thundering cauldron, and Mímisbrunnr, or Mimir's spring. Urd's well is under the root leading to Asgård. Mimir's source is under the root that reaches Jotunheim. Beneath the root that reaches Niflheim springs Hvergelmir, the river from which all the eleven rivers of creation originate.
Content
1 Residents
2 Yggdrasil in legends
3 Sources
4 On the topic elsewhere
Population
On the branches of Yggdrasil sits an all-knowing eagle with the Veðrfölnir falcon between its eyes. The dragon Nidhöggr leaves Yggdrasil's roots in Niflheim. The squirrel Ratatosk acts as a messenger between the Eagle and the dragon. Likewise, it bites the tree, causing rotten branches to come off. In addition to these, four deer live on the branches: Dain, Dvalin, Duneyr and Durathror. The deer represent the four winds. Deer eat tree leaves and buds. As the tree suffers from the destruction caused by its inhabitants, the three Norns who live by the well of Urd pour a mixture of mud and water on the branches of Yggdrasil every day.
Yggdrasil in legends
Odin gave Mimir one of his eyes to drink from Mimir's spring flowing beneath Yggdrasil to gain wisdom. He hung himself in Yggdrasil for nine days to learn the secrets of the runes. The gods meet daily and hold their court at the well of Urdi. Yggdrasil, which suffered badly after Ragnarök, is to become the source of new life.
Yggdrasil; the picture is from the English translation of the Prose Edda from 1847.
Source directly: https://fi.wikipedia.org/wiki/Yggdrasil