Much like the Fates in Greek mythology, Norse mythology has a set of goddesses controlling fate and shaping the destiny of men. These are called the Norns: three sisters who are personifications of the past, present and future. Skuld ("being"), Verdandi ("necessity"), and Urd ("fate"). Some sources speculate that these sisters were descendants of the giant known as Norvi- from whom Nott ("night") was born. Whatever the case, the Norns were very special. The Gods could neither question nor influence their decisions. The Norns were located under the great tree Yggdrasil near the Urdar fountain.
Their purpose is not always clear, but they were said to have been there as to warn the Gods of future events, teach them how to use the present, and remind them of the lessons learned in the past. It was not uncommon for the Gods to visit the Norns, as they sought advice and wisdom from them. Odin was a frequent visitor.
Because the Norns were personifications of time, each sister represented a different age and character. Urd (Wurd-"Weird") appeared as an old and decrepit woman, constantly looking over her shoulder and behind her. Her face was lined with deep wrinkled and she had an expression of thoughtfulness. Verdandi, the second sister, was young and fearlessly stared straight ahead. Skuld, the last sister, was a representation of the future and was often seen as cloudy or heavily veiled, looking away from where Urd was. In some representations, Skuld is holding a scroll that has not been opened yet.
Their main job was to spin and weave the threads of fate. They would then attend to the sacred tree, often bringing it water from the Urdar fountain and putting fresh clay around its roots. They would watch the golden apples that contained knowledge and only allowed Idun to pick the fruit. It is said that these apples were what gave the Gods renewed youth and beauty. The webs they spun were giant: one weaver stood on a mountain in the east, one stood in the middle of the western sea, and the other worked on the thread in-between. The threads varied in color, depending on the events they foretold. A black thread, for instance, would mean death. As the sisters worked, they chanted and sung songs. Stories say that they spun their webs blindly, as if reluctantly following Orlog's (the universal eternal law)
wishes. Two of the sisters (Urd and Verdandi) were very beneficent and worked hard while the other constantly undid the work they had completed. She would often tear it to shreds if she was angry with it, and cause the other two grief.
Some stories say that there were two beautiful swans that inhabited the Urdar fountain. The Norns would feed and care for the swans, and should they wish to visit Earth they would occasionally take the form of these birds. They would make trips to tell mortals of the future or to offer advice. It was always considered wise to listen to whatever it is they said, even if it was not good. However, the Norns weren't the only ones who traveled to give messages to men. There were several other, less important, guardian spirits who would lavish men with things. The Norns would sometimes be present at births and deaths.
You can see reference to them in various types of literature. They would appear as fairies or witches.
For instance, Shakespeare's Macbeth:
"1st Witch: 'When shall we three meet again: in thunder, lightening, or rain?'
2nd Witch: 'When the hurlyburly's done, when the battle's lost and won:'
3rd Witch: 'That will be the ere of the set of sun.'"
They had several other names, such as Vala or prophetesses: they had the power of divination, which was held in high esteem by northern nations.
" Oh, manifold is their kindred, and who shall tell them all?
There are they that rule o'er men folk, and the stars that rise and fall:
They love and withhold their helping, they hate and refrain the blow;
They curse and they may not sunder, they bless and they shall not blend;
They have fashioned the good and the evil,they abide the change and the end. "
** Note: There is, as with many types of mythology, variation between sources. This is by no means a complete summary of this topic- just a look into it. This is mythology, and I do not claim any of it to be "true" or set in stone, so to speak. **
Myths of Northern Lands by H.A. Guerber
Norse Mythology: Great Stories from the Eddas by Hamilton