Galadriel is the only daughter of Finarfin, prince of the Noldor. She is born in Valinor during the Years of the Trees. During the great perturbations at the end of that period, she comes to Beleriand with most of the Noldor. She lives nominally with one of her brothers, but spends much time at the court of Thingol and Melian in Menegroth, where she falls in love with, and later marries, the noble Celeborn.
Both Celeborn and Galadriel survive the War of Wrath. It is said in one account that, journeying eastward, they come to a Nandorin settlement in the valley of the Anduin. They take up its kingship, and call it Lothlórien. They have a daugher, Celebrían, who marries Elrond Half-elven of Rivendell.
During the Second Age, when the Rings of Power are forged, Galadriel becomes one of the Three Keepers of the Three Rings of the Elves. Her Ring is Nenya, the Ring of Water. Conscious of Sauron's power, and wishing to thwart it, she does not use the Ring so long as the One Ring is in Sauron's hands. However, during the Third Age, when the One Ring is lost, she puts it back on. Its power may be related to the Mirror of Galadriel, a large bowl of water in which visions of the future may be seen.
She hosts the Fellowship of the Ring after their escape from Moria. When she hears of their arrival in the woods, she sends word to the elf guards to remove their blindfolds. When she meets them in her tree dwelling, she gives each member of the fellowship a searching look, testing their resolve (Boromir regards this test as a temptation). She, in turn, is tested when Frodo Baggins later offers to place the One Ring in her keeping. Knowing that its corrupting influence would make her "great and terrible", she declares, "I pass the test" and refuses the Ring. She says that she will "diminish," but the reader does not know enough yet to understand what this means. When the time comes for them to leave, she gives each member of the fellowship a gift and an elven cloak, and outfits the party with three boats and much waybread.