Yggdrasil is the world tree in Germanic mythology. There is no explanation or tale explaining its creation. The Nordic cosmographical world is divided into three trisentric levels with a space separating each plate. The roots of this sacred Ash tie together the three levels of the world, and its branches the very heavens.
In the first level of the world there is Asgard, Vanaheim, and Alfheim. The second level contains Midgard, Jotunheim, Nidavellir, and Svartalfheim. The third houses Hel and Nifelheim. The world tree is rooted in the realm of the Aesir, the realm of the frost giants, and the realm of the dead.
The tree is subject to constant death and renewal. A dragon named Nidhogg gnaws at the roots and a squirrel called Ratatosk on the branches. Deer graze off the tree and leap on it. An eagle sits on top of the world tree stirring up the winds of the world with its wings. The squirrel runs up and down the tree delivering vindictive messages between the eagle and Nidhogg.
The tree stays green and rejuvenated with the aid of the Norns.They sprinkle the tree with clay and water from the Spring of Urd to prevent Yggdrasil from rotting away. The spring of Urd, lies in Asgard and has very strong properties. Everything that touches these waters turns white. This well is also known as the well of destiny. The gods hold council by it.