Source: pantheon.org
In Norse mythology, the Norns are the demi-goddesses of destiny. They control the destinies of both gods and men, as well as the unchanging laws of the cosmos. They are represented as three sisters: Urd ("fate"), Verdandi ("necessity") and Skuld ("being"). They live at the base of the World Tree Yggdrasil in the realm of Asgard.
Nothing lasts forever, and even the mighty Yggdrasil is subject to decay. The Norns try to stop this process, or at least slow it down, by pouring mud and water from the Well of Fate over its branches. This magical liquid stops the rotting process for the time being.
In other myths, the Norns were thought to give assistance at birth, and that each person has his own personal Norn